Question: Is masturbation a sin?
Answer: This is a question that has puzzled Christians for centuries. The short answer is that nowhere in the Bible is masturbation referred to as a sin. In fact, the word is not even in the Bible. Having said that, I feel that excessive masturbation coupled with pornographic fantasies is an addiction that needs to be broken. Here is an excellent article that deals with every Scripture related to this issue.
The article is a bit long, but very thorough. I don't agree with everything the author says on his website, however, I feel that the author does a good job answering tough questions from a Biblical perspective. Since the author has researched this more thoroughly than I have, I'll defer to him on this matter.