I can't tell you an exact statistic but I do know that it is extremely rare to contract Hep C through sex. I have done some research on this subject because my mother has Hep C. Most often it must be passed through some type of blood to blood contact. I work at a family planning clinic so I will see if we have any info. that gives specific percentages or statistics tomorrow and will get back to you. Also, I am sure you may have considered this but perhaps you should be checked for other sexually transmitted infections in the next 4 to 6 weeks and get an HIV test. HIV tests should be done about 6 weeks after exposure for a baseline reading of antibodies and then again 6 months later. Those with Hep C are considered high risk for HIV because, minus sexual intercourse, the modes of transmission are the same. Of course, not knowing how this person you were with got Hep C or anything about their history, I may be assuming alot. You obviously know more about them than I but just in case...