Background & Objectives: Spironolactone is a diuretic and antiandrogenic drug and is used in the treatment of hypertention 'secondary hyprealdosteronism congestive heart failure' cirrhosis of the liver, nephrotic syndrome 'androgenic alopecia' gynecomastia and hirsutism. In this research, the effects of spironolactone on the serum LH, FSH, testosterone, dihydrotestosterone, and changes in body weight and testicular tissue in adult male rats, were studied.

 Methods: For this purpose 190 10 g male wistar rats (n=40) were randomly divided into the following grups: control, sham operated (received water) and 25, 50, 100 mg/kg oral spironolactone treated groups. After 14 days body weight and testis weight under laboratory methods, were measured and blood samples were taken from heart and used for the measuring of LH/FSH/testosterone and dihydrotestosterone and then the rates' testes, in order to evaluate the histological changes, were removed and weighed and after obtaining tissue section and staining through HE, they were studied.

 Results: Serum LH level showed a significant increase and testosterone and dihydrotestosterone levels showed asignigicant decrease in 100mg/kg spironolactone treated group ( p 0.05 ) and there was no significant difference among serum FSH level, body weight and testicular weight as compared to control group.

 Conclusion: It can be concluded that oral administration of spironolactone maximum dose for 14 days could increase serum LHlevel and decrease testosterone and dihydrotestosterone levels.