During the last 11 years, 1920 azoospermic men were examined and infertility was attributed to bilateral asplasia of vasa deferentia in 38 subjects (1.9% of cases). Epididymal biopsies showed sperm granulomas in the interductular spaces with increased phagocytosis. The sperm granuloma might be a factor in initiating humoral and cell mediated immune reaction, which interferes with sperm motility and fertilizing capacity of sperm. This would explain the poor pregnancy rate achieved with artificial insemination using sperm obtained from a created spermatocele in the head of the epididymis.