SUMMARY:Varicoceles are abnormal tortuosity and dilatation of the veins of the pampiniform plexus that drain the testis.The pathophysiology of testicular damage in varicocele has not been completely understood. However there is an increasing body of evidence pointing towards the role of reactive oxygen species and oxidative stress in the pathogenesis of varicocele related subfertility. In the present study we examined the role of proanthocynidin-rich ethanol extract of grapefruit seed as an antioxidant in protecting the testis against damage in experimental varicocele. Three groups of rats were constructed as the first group had intact rats; experimental bilateral varicoceles were established by complete ligation of the left and right main spermatic veins in the later two groups. The third group had in addition daily gavage administration of 10mg/ kg body weight ethanol extract of grapefruit seed. Eight weeks after varicocele induction, bilateral testicular weights, bilateral testicular volumes, bilateral caudal epididymal sperm characteristics, and bilateral testicular histology and serum hormone levels were tested. It was found that the testes of grapefruit seed extract treated animals had better functional and histological profiles compared to the untreated varicocelized animals. These results indicated the effectiveness of grapefruit seed extract for preservation of testes function morphology in varicocelized subjects.