Sperm function was assessed in 19 men 3-10 years after cessation of gossypol treatment and 2-9 years after recovery of normal sperm density. Nineteen normal fertile men of similar age served as the controls. The zona-free hamster egg-sperm penetration assay (SPA) revealed a highly significant difference (P less than 0.01) in the penetration rates between the treated and the control groups. Hormone assays indicated that there were no significant differences in circulating levels of luteinizing hormone (LH) and testosterone (T) between the two groups, but the follicle stimulating hormone (FSH) level of the treated group was significantly higher than that of the controls (P less than 0.05). The results showed that sperm function in the treated group was lower than that in the control, which may be a result of persistent gossypol-mediated damage to the testes.