The general male population has shown a long-term decline in sperm count. Induced hormonal imbalance can produce adverse reproductive effects in men, especially decreases in sperm count. One suggested cause for a decreased sperm count is a reduction in the number of Sertoli cells. The authors assessed numbers of Sertoli cells in testicular biopsy specimens obtained from azoospermic men between 1989 and 1999. The number of Sertoli cells per tubular area or circumference did not vary by year of biopsy among the tissue samples during this 10-year period. Patient age, taken as a measure of exposure duration to hypothesized abnormal hormonal environment, did not affect the number of Sertoli cells. Since no reduction in the number of Sertoli cells was observed, other pathogenic factors may be the cause of long-term decreases in sperm count.