The possibility of HIV infection can be ruled out after two years of high risk. AIDS is a chronic infectious disease caused by human immunodeficiency virus infection, and there are more ways of transmission. The recognized ways of transmission are sexual contact transmission, vertical transmission from mother to child and blood and body fluid contact transmission, especially after unclean sexual contact, if the other party has AIDS, it can cause HIV infection through local mucous membrane breakage by sexual route. Therefore, after high-risk sex, first of all, you should pay attention to observe whether you have any special symptoms of infection, and at the same time, you need to regularly check the relevant indicators, and in the first three months after exposure, you need to conduct a monthly antibody screening, if there is no problem, you can basically rule out. However, in some special people, such as patients who use immunosuppressants or have other underlying diseases, it may lead to false negative antibodies, so it is necessary to extend the review time, in six months and a year, respectively, two more tests, if negative, can be ruled out, and two years can be ruled out the possibility of HIV infection.