Objective: Polycystic ovarian syndrome (PCOS) is the most common endocrinological disorder in women of reproductive age and hyperandrogenism is a prominent feature of PCOS resulting in infertility and increased risk of developing metabolic disorders including insulin resistance (IR), abdominal adiposity, glucose intolerance and cardiovascular diseases. Spironolactone (SPL), a non-selective mineralocorticoid receptor (MR) antagonist, has been in wide clinical use for several decades. In this study, we investigated the effects of SPL on IR and metabolic disturbances in letrozole-induced PCOS rats. Design and method: Eighteen adults female Wistar rats were randomly divided into 3 groups and treated with vehicle, letrozole (LET; 1 mg/kg) and LET + SPL (SPL; 0.25 mg/kg), p.o. once daily for 21 consecutive days. Results: Results showed that LET treatment induced PCOS characterized by elevated plasma testosterone and luteinizing hormone (LH) accompanied with increased body weight and visceral adiposity, IR, glucose intolerance, dyslipidemia and altered histomorphological ovaries. Treatment with SPL however attenuated the elevated testosterone in LET-induced PCOS model accompanied with a reversal in all the observed alterations. Conclusion: Taken together, analysis of the physical, biochemical and histological evidences shows that the protective effect of this very low dose spironolactone may be through its anti-androgenic mechanism. In conclusion, this study shows for first time, the protective effect of spironolactone at this dose against insulin resistance and metabolic disturbances induced by experimental PCOS. The protective mechanisms appears to be through suppression of elevated circulating testosterone. Therefore, SPL alone at this very low dose might be very effective as against its combination with other known anti-androgenic drugs in the treatment of characteristic features of PCOS.