Research linking psychological inhibition to physical illness led us to examine whether human immunodeficiency virus (HIV) infection might progress more rapidly among gay men who conceal their homosexual identity than among those who do not.We also sought to determine whether any accelerated course of HIV infection among "closeted" gay men might be attributable to differences in health-relevant behavior (e.g., health practices, sexual behavior) or psychosocial characteristics (e.g., depression, anxiety, social support, repressive comping style). Data came from a longitudinal psychosocial study associated with the Los Angeles site of the Multicenter AIDS Cohort Study. Eighty gay men, HIV-seropositive but otherwise healthy at study entry (CD4 T lymphocytes = 30-60% of total lymphocytes), were examined at 6-month intervals for 9 years. Indicators of HIV progression included time to a critically low CD4 T lymphocyte level (15% of total peripheral blood lymphocytes), time to AIDS diagnosis, and time to AIDS mortality. On all measures, HIV infection advanced more rapidly in a dose-response relationship to the degree participants concealed their homosexual identity. Sample characteristics and statistical controls ruled out explanations based on demographic characteristics, health practices, sexual behavior, and antiretroviral therapy. Mediational analyses indicated that observed effects were not attributable to differences in depression, anxiety, social support, or repressive coping style. HIV infection appears to progress more rapidly in gay men who conceal their homosexual identity. These results are consistent with hypotheses about the health effects of psychological inhibition, but further research is required to definitively identify the psychosocial, behavioral, and physiological mechanisms underlying these findings.