Three groups of male homosexuals: AIDS (n = 19), HIV seropositive (n = 15), and seronegative partners of seropositive subjects (n = 15), were compared to a heterosexual seronegative control group (n = 13). Twice daily evaluations (8 A.M. and 5 P.M.) of plasma levels of beta-endorphin, ACTH, and cortisol were done by radioimmunoassay. Seropositive subjects and their seronegative partners showed similar levels of neurohormones: 1. An elevation in the ACTH/beta-endorphin ratio in the plasma, (C = 0.69 +/- 0.84, AIDS = 0.44 +/- 0.32, S+ = 0.42 +/- 0.28, and S- = 0.42 +/- 0.5); 2. A loss of normal relationship of the coupling ACTH/total cortisol, (C = 0.00035 +/- 0.00028, AIDS = 0.00042 +/- 0.0034, S+ = 0.00074 +/- 0.00068, and S- = 0.00072 +/- 0.0008. Neuroendocrinological disorders have been observed in HIV-infected subjects and in their seronegative partners. These could be related to their sexual behavior, as well as to the HIV infection. If this last hypothesis is confirmed, the ACTH/beta-endorphin and ACTH/cortisol ratios may be seen as possible early signs of HIV infection.