Yes, it is possible for you to become infected with HIV through oral sex. There have been a few cases of HIV transmission from performing oral sex on a person infected with HIV. While no one knows exactly what the degree of risk is, evidence suggests that the risk is less than that of unprotected anal or vaginal sex.

Blood, semen, pre-seminal fluid, and vaginal fluid all may contain the virus. Cells in the mucous lining of the mouth may carry HIV into the lymph nodes or the bloodstream. The risk increases  if you have cuts or sores around or in your mouth or throat if your partner ejaculates in your mouth if your partner has another sexually transmitted disease (STD). If you choose to have oral sex, and your partner is male, use a latex condom on the penis.

If you or your partner is allergic to latex, plastic (polyurethane) condoms can be used. Research has shown the effectiveness of latex condoms used on the penis to prevent the transmission of HIV.

Condoms are not risk-free, but they greatly reduce your risk of becoming HIV-infected if your partner has the virus. If you choose to have oral sex, and your partner is female, use a latex barrier (such as a dental dam or a cut-open condom that makes a square) between your mouth and the vagina. Plastic food wrap also can be used as a barrier.  

The barrier reduces the risk of blood or vaginal fluids entering your mouth.