Vlad Dracula("Tepes") was the son of Vlad Dracul, abd I guess he's the one you're refering to. He married three times, but the identities of these women are not known(many people claim to know the "truth", though). I've translated this for you - it might give you an impression of all the confusion:

"There's a myth about Dracula's first wife throwing herself from the tower of Poienari to escape the turks, and some sources claim that her name was Elzbieta/Elisaveta, a Romanian noble lady. On the other hand, Vlad's first wife was also said to be named Cnaejna Báthory of Transilvania, who comitted suicide in 1462, which was the year he was driven out of Romania. This fit well to the claim that she was of noble birth - the Báthory family was an Eastern(and Central)European noble family. Both a Polish king and the infamous murderess Elżbieta Batory were members of it. But Dracula's mother is usually refered to as Cneajna, which is probably the same name as Cnaejna. of course it's possible that he married a woman whose name was that close, or even identical to his mother's, but the name Cnaejna is not mentioned anywhere else.
The next wife was either Jusztina or Ilona Szilàgyi, a cousin of Hungarian king Mattias Corvinus. János Hunyadi(king Mattias' father) was married to Erzebet Szilàgyi, and her brother Osvát Szilàgyi had the daughter Jusztina with his wife Ágota Szeri-Pósa. This wife bore two sons, Vlad and Mihail, later voivods."

Royals in Romania(and other places in Europe too!) had a hard time staying alive, and the family of Dracula had many enemies. Even though some people claim to be Dracula's descendants, they can not prove it, and it's not likely to be true; Dracula's sons died young, and the bloodline died with them. The closest you get is the descendants of Dracula's older brother, but of course, it's impossible to prove anything. Sadly enough, popular culture has ruined what was left of reliable information; some people are so obsesses with the idea of being related to him, or finding connections between him and present day royality, that they use their imagination to prove their teories. The result is of course that most of the information you get is unreliable, which is sad. I'm not sure why anyone should want his castle either - Poienari is just a ruin;)
If there are any descendants of him left, they're probably wallachian farmers whose ancestress had an affair with Dracula;) - and remember: if you want your children to be proud of who they are, or get a little respect, it's pretty safe to tell a small lie about the celebrity you're related to; after all, it's not an easy task to prove you wrong. If he got an illegitimate child(which is likely - he had lots of mistresses), the child itself would either be told the truth, claim his right to the thrown and be killed, or live a happy life without knowing.

But still, being related to him would have been cool!;)