To study the affect of bilateral varicocele (grade 3) on impotence and male infertility patients, 29 patients were selected from an outpatient clinic during 15 May 1998 to 15 August 1999 (the mean age was 33.9 +/- 6.3), 15 patients complaining of erectile dysfunction and 14 patients complaining of male infertility. The mean duration of impotence was 3 +/- 2.3 years and for male infertility was 6 +/- 2.5. All organic and psychogenic causes related to impotence and male infertility except bilateral varicocele (grade 3) and low plasma testosterone were excluded by clinical and laboratory investigations. Twenty males with normal erection and fertility were included as controls. Detailed medical history and complete physical examination included measurement of testicular size by orchiometer; semen and hormonal parameters were measured for all patients and control. In impotent patients left and right testicular volume was significantly decreased (p < .05), while in male infertility patients left and right testicular volume was highly significantly and, significantly decreased (p < .005, p < .05) compared to controls. In male infertility patients, left testicular volume was highly significantly decreased compared to impotent patients (p < .005). The sperm count and semen volume in impotent patients was significantly decreased (p < .05, p < .01), but no significant differences were found in sperm motility and abnormal forms, while in male infertility the sperm count was highly significantly decreased (p < .005), the sperm motility was significantly decreased (p < .05), the abnormal form was significantly increased (p) < .05), but in the semen volume there was no significant difference compared to controls. In impotent patients the sperm count was significantly increased and abnormal form was significantly decreased compared to male infertility (p < .05). The mean serum testosterone was significantly decreased in impotent patients (p < .01), and highly significantly decreased in male infertility (p < .005) compared to controls. The mean serum FSH was significantly increased in male infertility (p < .05) and nonsignificant in impotent patients compared to controls. The mean serum LH and prolactin levels were nonsignificant in both impotent and male infertility patients compared to controls, but LH was significantly increased in impotence compared to male infertility patients (p < .025). Therefore, bilateral varicocele (grade 3) is associated with significant reduction in testicular function with significant increase in serum levels of FSH and LH, which may cause erectile dysfunction and male infertility.