Background Sildenafil (Viagra) is widely used for the treatment of erectile dysfunction under various etiologies. Unfortunately, chronic administration of sildenafil negatively affects fertility. The aim of the present study is to investigate the improvement role of sesame on the testis alterations caused by long-term administration of sildenafil on albino rats. Results Light microscopically observations showed that overdoses of sildenafil had provoked tubular and interstitial histological alterations. Tubular degeneration and abnormality in the germinal epithelium of the seminiferous tubules included spermatocyte degeneration and arrest of spermatogenesis. Sperm count and motility were negatively affected by sildenafil. These alterations were improved by sesame feeding. Conclusion Sesame intake improve the side effects of prolonged treatment with sildenafil significantly. These results demonstrate the pivotal role of sesame that may improve male infertility.