In 210 subfertile men there existed a significant positive correlation between serum FSH [follicle stimulating hormone] and LH [luteinizing hormone] (0.41). No correlation was observed between the gonadotropin levels and testosterone. In contrast to this FSH and LH were negatively correlated with the natural logarithm (ln) of the sperm count/ml ejaculate (-0.44 and -0.18, respectively). When the positive correlation which existed between FSH and LH was used to calculate partial correlation coefficients, the coefficient between FSH and ln sperm cound hardly change (-0.41) the coefficient between LH. Ln sperm count on the other hand became insignificant (-0.05). This suggests that spermatogenesis influences FSH serum levels in subfertile men by a decreased suppression when sperm production is diminished. Testicular biopsies taken from 97 of these patients were used to determine biopsy scores. These scores showed a significant negative correlation with FSH (-0.34) and a positive one with ln sperm count/ml ejaculate (0.45). Interestingly the biopsy score of 16 patients who fertilized their wives, was found to be higher compared with the score of the other patients who did not fertilize. The number of sperm/ml ejaculate and the FSH values of these 2 groups of biopsied patients were not significantly different. The biopsy score is a better parameter for the evaluation of oligospermic men than either sperm count or FSH serum values.