The common histological abnormalities on testicular histology in 79 infertile virile men were hypospermatogenesis (35%), severe testicular atrophy (29%) and maturation arrest (19%). Sperm counts showed no correlation with testicular size, gonadotropin levels and histological classification. There was elevation of mean follicle stimulating hormone levels in males with maturation arrest (5.8±3.8 lUlL) and Sertoli-cell only syndrome (21.7±3.4 lUlL). Patients with severe testicular atrophy had elevated luteinizing hormone (15.1±11.8 lUlL) as well as follicle stimulating hormone (49.8±11.4 lUlL) levels. Patients with hypospermatogenesis and focal atrophy had normal luteinizing hormone and follicle stimulating hormone levels and all of them had normal testosterone and prolactin levels. Treatment with gonadotropins or clomiphene citrate was ineffective.