The presence of antibodies against spermatozoids was evaluated in one person with AIDS and six homosexuals (HS). Indirect immunofluorescence was utilized along with immunoenzymatic trial with peroxidase (ELISA) in order to detect antibodies class IgG towards spermatozoids and their membrane proteins. Optic densities of the following groups of patients were compared: 1) One patient with AIDS. 2) Six homosexuals (HS). 3) Three HS with cells OKT8 greater than 30%. 4) Three HS with cells OKT8 less than 30%. 5) Three men with auto-antibodies against spermatozoids + infertility. 6) Two men without auto-antibodies against spermatozoids + infertility. 7) Five women, spouses of the infertile men. 8) Five multiparous with more than 3 pregnancies. 9) One man with orchitis. 10) Ten fertile and healthy (C.G.) heterosexual persons. The patient with AIDS and the one with orchitis had the highest optic densities (OD), (groups 1 and 9). Groups 8 and 10 had the lowest, non-significant values. Groups 2, 5 and 7 ranked second in place in reference to O.D. Groups 3, 4 and 6 ranked third in O.D. values. Groups 8 and 10 differed significantly at P less than 0.005 compared with the others. The presence of antibodies against spermatozoids was considered as an important factor associated with AIDS and previous states of the AIDS detected by OKT8 greater than 30% of lymphocytes. The IIF and ELISA were able to detect antigenic system in spermatozoids with allelic form, which may be similar to the mice locus t, or a new tissue specific system.