Let me clear this up: Tarantino said himself that it's up to the viewer to decide what's in the briefcase. There is no absolute answer to this at all. Of course, there are excellent theories that make total sense, but inevitably, it's the viewers interpretation.

I believe that Marcellus made a deal with the devil to make Mia Wallace marry him in exchange for his soul, and she does but she doesn't love him, so the devil fucked him over. So Marcellus sends Samuel L. Jackson and John Travolta to go into those guys house where he eats there cheeseburger etc and John Travolta gets the case and puts the code in "666" which contains Marcellus soul. Once Marcellus gets his case back into his possession he has that gunfight with Bruce Willis and he gets fucked (again) literally this time by those hicks, so the devil won, and another reason is near the end Tim Roth is stunned and almost hypnotised by what is inside the case because the soul is supposed to be a beautiful thing. And I think the bandaid is on Marcellus neck because it's covering up a tattoo of "666" because the devil owns him? Idk that's what I think anyway.

Vincent Vega for one would not loose his concentration for neither gold or jewelry, there was something in that briefcase that he had never seen before, but still imidiatly recoqnized for what it was. Namely something as powerful, unique and amazing as a soul. And there is one more thing: Look at those kids in the hamburgerscene. Are you telling me they ripped Wallace off in a jewelrydeal?? No way, they wouldn't even be in touch with anyone in that business normally. So why are bibelreading Bret making a deal with mr Evil himself? Because he is a Gad man.
-But they fucked mr Wallace, so why would these Christian kids cheat a mafioso? They sold him the idea that his wife would love and respect him if he gave them his soul to trade with the devil. What they knew, and mr Wallace never understood, is that to mr Wallace, the soul was gone even before it came in their hands. Knowing that he would try to trade it with the devil, they pretended to help, but with the intencion to get it back in the kingdom of Gad. -"I'm sorry that things got so fucked up between us an mr Wallace"... Bret ment it. It's just that he didn't expect this, him working for Gad and all. And one last thing: The gunshotmarks in the wall behind Jules and Vincent were there allready before the shooting. And Amanda Plummer doesn't screem the same line in the two identical robberyscenes. But that don't mather. Cause it's a pulp fiction.

It was "The Cosmic Cube" from Captain America! Seriously, watch the extra scene after the credits in the 2011 movie Thor, Samuel L Jackson opens the briefcase and finally reveals what was in it. Tarantino you are a genius for arranging that extra scene to finally answer everyone's question after all this time! Kudos

It can't be a "soul" because everybody who see's what it is, instantly gets a boner and knows what it is. I'm pretty sure nobody knows what a soul looks like. As for the gold, yes its plausible but unlikely since its heavy. Diamonds, maybe. The only reason it glows orange is because somebody on the set threw in an orange bulb, it wasn't in the script or anything. They liked it so they went with it. As for the combination, it's Quentin Tarantino, he always does shit like that. And I think the person 2 posts above me needs to learn how to spell. Jesus that was annoying to read

Guys guys,

I have no idea what was in the case. But I know for a fact that Wallas has a big ugly scar on the back of his neck in REAL LIFE. There is a movie called animal that Vig made and directed. The opening scene in Animal the movie, he has a big scar on the back of his neck....exactly where the bandaid was.
Just a guess on the briefcase is....it has to be something gold....but not full of gold or they couldet just move it around so easy. I am thinking the guy brett is a smart guy...he might have worked at a place where he could have stolen something gold like king tut made of gold....when the rober ringo says is that what I think it is? It had to be something everyone knows what it is but is much more than just gold....Ringo says it's beutiful and stops him in his tracks....also the same for vincint....it stops him in his tracks as well....simple gold would not do that. Thats only a big guess on my part and I am most likely wrong! But I do know for sure that soal stealing stuff is sooooooooo wrong.....how does somebody keep a soal in a briefcase? Also if it was a soal....how would Ringo the rober have any idea what a soal would look like. You think he just opened it up and there was a stamp that said this is a human soal that glows?
Watch the movie Animal and you will see that he has a real scar on his neck.

Considering that there seems to be a common thread that QT is deliberately being secretive (it DOES make the whole idea cooler), and since I know this film off by heart, I have a theory with film based evidence...
I believe that what is in the suitcase is in fact Marcellus Wallaces soul.
Firstly, the band aid IS in fact representative of removing the soul from the back of the neck.
Secondly, the reactions of those who see the contents. Diamonds don't glow gold. Vincent looks gob smacked when he sees it. Do you think that a renowned gangster like him would be that shocked by seeing diamonds, remembering that Vincent Vega (though different actor) has already seen the diamonds from Reservoir Dogs when he was involved with stealing them. And of course Ringo's reaction is almost comatose at seeing it.
Third, when Jules steps sideways after the failed attempt at shooting him, bullet holes reveal that the bullets have somehow gone straight though him. So, why WOULD god come down and stop the bullets? Because even though Vincent and Jules are gangsters, they're doing gods work by retrieving stolen souls. Hence the 666 code. How do you think these young kids could do ANYTHING to someone as powerful as Wallace unless they were doing rituals and accidentally took the wrong soul. Something that even powerful people with guns can't prevent.
God chose these two to do his work, after they successfully retrieve MW soul. Jules takes the sign and continues gods work. Vincent doesn't listen to god and consequently meets his demise.

I'm not a religious person by any stretch, but watch the movie again with what I said in mind and I guarantee you'll agree!!

I found this page very interesting. The film will never be the same to me again after reading this:

http://www.snopes.com/movies/films/pulp.asp

It was a cheeseburger.... Inside the briefcase was a cheeseburger.

It was whatever you want it to be.

Case Contents
On set : Orange Lightbulb
According to the man: A small nuke in homage to
Robert Aldrich's "Kiss Me Deadly"
Meant to be: up to the viewer
Band-Aid
On set : Check the movie "Undisputed" (shower scene) - V has some gnarly scars
Meant to be : a possible release point of the soul

Ok it has to be said,,,vincent vega from pulp fiction and vic vega from resivoir dogs are not the same guy,,,perhaps they are brothers, only a theroy of course but it makes sence to me, the movies take place in the same area and around the same time, marcelus wallace is mentioned in resivoir dogs although he isn't acctually in it,,,as far as what is in the breifcase, diamonds, mw's soul, gold bars, who knows, for a while I thought it was full of herion but recently I watched both movies back to back and tho their are referances to each other in both they are seperate stories entirely,,,I don't believe that the diamonds are in the case because Mr. Pink got away with them,,,if it was gold bars it would be too heavy to carry in one hand,,,but I hardly believe that mw's soul was a pure and beautiful thing so the beauty shining from the case, probly not his soul...maybe it was salvation in the case

As a revision to what I said before, Mr. Pink got out with the diamonds...but you hear the police stopping him in the background from inside the warehouse,which means the diamonds go to the police,,,figured I should correct myself before some d-bag does the inevitable and jumps all over my little mis-speaking to try and make themselves feel better about being a no life pathetic loser,,,

the band aid - ving cut his neck shaving, but a band aid on the cut and qt left it in.

breifcase - it's a 'mcguffin' (hitchcock term meaning it's just a thing used to make the action take place - there is nothing in the briefcase),

Because the sequence is mix in the film. All of your question is answer in the film it self. Look at it like all the symbols are a premonition.

The band aid on Wallace neck came from the fact he will have bad time with Butch

The reason Wallace throw Tony you will find it when you'll see Vince shaking hand of Mia (Same thing Tony's does. Wallace used to knew the secret...)

The car of Vince hapened to be wreck by imself on the house of Lance.

All question you ask about someting in the film have is own anser into the film itself.

So...If I'm right... what do you thing there is in the briafcase?

In the briefcase you will find the light.

Jules is the righteous man. He is the one who, in the name of charity and good will, shepherds the weak through the valley of darkness. He show the light, from the briefcase, to the weak. They see the liberty. They find there way out of the valley of darkness. That is wy Wallace want the briefcase for imself.

Vincent does not beleive on wath he just saw from the briefcase "And I will strike down upon thee with great vengeance and furious anger those who attempt to poison and destroy my brothers." That's why he die.

Ezekiel 25:17- "The path of the righteous man is beset on all sides by the inequities of the selfish and the tyranny of evil men. Blessed is he who, in the name of charity and good will, shepherds the weak through the valley of darkness, for he is truly his brother's keeper and the finder of lost children. And I will strike down upon thee with great vengeance and furious anger those who attempt to poison and destroy my brothers. And you will know my name is the Lord when I lay my vengeance upon you. "

And now! Who the "hell" is the Brett team and what is Marvin real mission?

Bible says that the anti Christ will bear the mark 666 on his body. In the Omen movies the 666 is a birth mark in the hair line. Marcelleus is bald? I think the band aid covers the birth mark 666. And the combo to the brief case is 666.

Get ready to have your minds blown!
The answer to what is in the briefcase is not a simple thing to figure out. You actually have to do a ton of other and behind the movie research. I have figured it out and would like to explain what I think I may have discovered. Here are the things that we know:
The Briefcase had a gold reflection and anyone who looked at it was baffled and awed.
We also know that the combination to the suitcase was 666.
We also know that Jules is extremely religious and gets shot at and is not hit.
The most important thing that I think people overlook, is the fact that they get the briefcase before they kill the people in the apartment.
So here is what is in the case and why. It is the Holy Grail. The reason it is, is because that it is written that anyone who looks at the Holy Grail will be humbled and dumbstruck. It is also written that Satan (Lucifer) will protect the Grail from ever reaching human hands (the suitcase combination). And finally anyone who has the Holy Grail and relies on God to strike down their enemies cannot be harmed. That is why they grab the case before they shoot everyone. This all comes together in one part of the movie. Just so everyone knows the bad-aid is because Ving Rhames cut his head while shaving it. The Bad-Aid has no relevance.

Gold bars in suitcase = are you on crack?
When Vincent picks up and flips the suitcase around to enter the 666 combo, he does it with ease and the case flops around appearing super light. Gold bricks are heavy, there is NO way he would be able to handle a case full of gold bricks with such ease. Give your head a shake. Re-watch the scene and see for yourself.

The gold light you see reflecting from within is a clue to a reference from a old James Bond movie. "The Man With Golden Gun". The same gold shine is also seen moments later when Vincent and Jules are shooting off thier guns at the guy hiding in the back room with a hand cannon, did you see that thing? It was bigger than him.

The light from the suitcase, is a golden gun.

P.S. The dumb guys had the golden gun because they were being the mules smuggling it across the border, and were supposed to return it asap but ended up getting high first.