Tamsulosin is alpha-1 adrenergic receptor antagonist which can alleviate the symptoms of urinary tract infections in elderly men because it reduces spasm of periurethral smooth muscle fibers and reduce the obstruction around bladder. Thirty animals were separated into 3 groups. Group (1) is control group, group (2) received 0.4mg/kg/day of the medicine orally for seven days. Group (3) received 0.4mg/kg body weight of the medicine for thirty days. Results: Group (2) liver tissue sections showed dilatation of portal vein, ballooning degeneration and necrosis of some hepatocytes while group (3) showed Severe congestion of portal vein with inflammatory cell infiltration and necrosis of most of hepatocytes. Microscopic examination of testis tissue slides of group (2) showed the tubules were less numerous, degeneration and necrosis of germinal epithelium while in group (3) testis sections showed reduced number of atrophied seminiferous tubules with interstitial edema. Vacuolation of spermatocytes and distortion of the process of spermiogenesis. It is concluded that tamsulosin can produce some histological effects on both liver and testis tissues when used for short duration (one week) while it can lead to harmful histological damage when it is given for long period (four weeks).