Dear Dr. McGovern,
I am wondering if it is possible to get any kind of serious disease (diseases other than a common cold or the flu) through French kissing or from a who is female performing oral sex on a male.
I would not expect hepatitis B or C to be transmitted in this way. As for other major STDs - syphilis can be transmitted if the female have an oral chancre. Gonorrhea can be present in the mouth (pharngeal gonorrhea) but this is infection is usually not transmitted this way. Herpes simplex can be transmitted through oral sex.