Slytherin House does not only take pureblooded wizards, regardless of the founder's preferences. I think the most obvious reason why Tom Marvolo Riddle was placed in Slytherin House would simply be because he has Salazar Slytherin's blood running through his veins. He also matches the ambition and slyness that Slytherins are famous for.

i think he got in because he seems so much like slytherine himself

Like others have pointed out, he is the heir of Slytherin. Besides, is there any other house that would have been right for him?

I don't think you have to be a pureblood to get into Slytherin (even though the books says you do), I mean, Snape got into Slytherin and he's a half blood. I think he got into Slytherin because he will truly use any means to get what he wants; that's a main Slytherin quality. For example; he makes himself immortal by killing other people.

I don't think you really have to be a pureblood to get in.
It's what you really want, isn't it?

Not everyone in Slytherin is a pureblood. Dumbledore told Harry in Chamber of Secrets that you choose which house you're in.

I agree completely. I was just thinking that too, about Snape being half-blood and getting into Slytherin. The Slytherins are just proud people and would never admit that anyone other than purebloods were accepted into their house. The Sorting Hat probably just makes exceptions for truly twisted people.

I don't really think it says anywhere in the book that only purebloods are allowed in Slytherin

Actually, contrary to popular belief, Slytherin does not only take purebloods. Salazar Slytherin preferred his house to be filled with pure blood, but the Sorting Hat was not designed for Salazar Slytherin's preferences alone. And, following the example of Tom Riddle, we can also use Snape as an example: he is half-blooded as well. How did he get sorted into Slytherin?

The Sorting Hat has gift from Godric Gryffindor with the approval of other Hogwart Founder.

Gryffindor wants student with courage within self
Slytherin wants student with line in the family of wizard (not necesarily means pureblood)
Ravenclaw wants her as much as brains and wise
Hufflepuff wants all other is to be rejected

Sorting Hat is design to look at students heart (as i belief, because he put you in the house you wanted)

in Tom Riddle case, like Harry (as raise by muggle) he didn't know what the house means to a students, but Tom Riddle is direct decendant of Salazar Slytherin and has its qualities of the blood line of the founder...

The sorting hat put Tom Riddle in Slytherin cause there's a lot of reasons.

First of all, he was related to Slytherin, so that's why he's a Parsemouth which is one of the reasons. The sorting hat put Snape in Slytherin too even though he's a half blood too. No one HAS to be a pure blood to be in Slytherin. As long as they are either cunning, sly, determined, or ambitious. Not everyone can match the perfact personality. For example Ron, he's scared of spiders and he's in Gryffindor full of brave people (but he's still brave and stuff XD)

I'm pretty sure Slytherin would prefer purebloods but he can't turn away his heir right?

He was the Heir of Slytherin, it was his destiny...

Seriously? He was the heir of slytherin! If Salazar got to create a student into exactly what he wanted it would of been Voldemort....

His personality traits fit Slytherin almost perfectly (save for the whole turning out completely evil thing) and it's not a requirement to be pureblood; that's just Salazar's opinion, as if the Sorting Hat cares...

Tom Riddle was sorted into Slytherin for quite a few reasons.

1. He's the heir of Salazar Slytherin
2. He has ALL the traits of a Slytherin
3. Its only Salazar's opinion for purebloods to be Slytherin's but it doesn't matter
4. He was blatantly born to be a Slytherin

I think Tom got in simply because that's where he wanted to be. He was full of evil before he came to Hogwarts (stealing and evilness) then he was sure to be in Slytherin.

I don't think it's because of blood either. Other wise there wouldn't really be any point of houses. If that were the case then why are the Weasly's in Griffindor?!

It was probaly his choice. The fact that he chose to be their.

Nat x

Slytherins could even have muggle borns in slytherin, just not that many. It would have been easy for him to get into it cause there was nothing wrong with his heritage from where Salazar slytherin was concerned.

It's not necessarily only for pure-ploods. Severus Snape himself was a half-blood. High possibility Riddle was sorted into Slytherin due to his ancestory. It's a very rare for muggle-borns to get into Slytherin though (as said by the snatchers in Deathly Hallows).

Well, he was the heir of Salazar Slytherin. So he kind of was a true Slytherin from the start, no matter what his blood type.

Besides, it's mentioned a few times in the book that there are very few true purebloods left in the wizarding world, and most families that claim to be pureblood are actually lying. Look at the Black's for example, who covered up any family members who didn't fit into their pureblood ideals. I would bet that no family is 100% pure, with some mixing happening here and there throughout history. So if Slytherin House only accepted purebloods, there wouldn't be very many people in it! I think it's more about believing in wizard purity and that they're better than muggles, rather than the actual pureness of the blood itself that gets you in.

Well, he was the founder's heir. Even the devil himself can make an exception for his great great great great grandson

Voldemort was probably more deserving to be in Slytherin than Slytherin himself. He defines what a slytherin's qualities are.

Here's a thought: he was sinister and had an evil mind, and Slytherin takes people with those charateristics and it helped that he was the heir of Slytherin himself.

They don't just take pure-bloods. They can take half-bloods and muggle-borns too. The sorting hat chooses the people who have the qualities of each house. It doesn't matter what your blood status is.

He was Salazar's descendant, and he has all Slytherin's virtues, so he was predicted to be in that house. No matter of his blood.