Summary Men from the Multicenter AIDS Cohort Study were classified as “susceptible” and “resistant” to HIV infection. Resistant men were still HIV antibody negative in 1993 and were estimated to have had >45 different anal intercourse partners (median, 92; range, 46–504) in the 2.5 years before visit 2 (1985). Susceptible men were seroconverters who were estimated to have had + percentage and number, and CD3+ and CD4+ number were higher in the resistant men. Logistic regression analyses were used to develop 50 bivariate models. Higher levels of neutrophils and CD8+ cells were included in four of the six best-fitting bivariate models, suggesting that each is associated with resistance to HIV-1 infection. These results support the hypothesis that CD8 + cells may modulate the outcome of HIV-1 exposure.