The semen and testicular histology of 39 patients with varicocele on the left side, and who had high ligation of the internal spermatic vein at our Department between 1975 and 1981 was examined. The grade of varicocele was neither related to density nor motility of the sperm, nor to the score count of the left testis. In 40% of the patients, both density and motility of the sperm improved after the surgical treatment. In 80% of the patients, the left testis weighed less than the right testis. In most of the patients, the score count of both testes was lower than normal, and was found to decrease remarkably in testes weighing less than 10 g. In 30% of the patients, the score count of the left testis was lower than that of the right testis. A positive correlation was recognized between score count and testicular weight, and no correlation was found between the score count of the right testis and sperm density.