Testicular biopsies from 81 patients with varicocele were evaluated by the score count method. Thirty-two patients sought treatment for infertility. Bilateral biopsies were performed in 47. Spermatogenesis was generally reduced in patients with varicocele, but there was no difference between the right and left tests. The testicular biopsy mean score correlated significantly with the total sperm count. There was no correlation between the size of the varicocele and the reduction in spermatogenesis. Although varicocele is nearly always left-sided, its mechanism of action must involve both testes. This mechanism is still unknown.