Harmine is a harmal-derived alkaloid with antioxidant properties. The morphine produces free radicals and plays a key role in the pathogenesis of kidney disease. This study was designed to evaluate the effects of harmine against morphine- induced damage to the kidneys of rats. In this study, 64 male rats were randomly assigned to 8 groups: saline and morphine treated groups; harmine groups (5, 10, 15 mg/kg) and morphine + harmine treated groups (5, 10, 15 mg/kg). Treatments were administered intraperitoneally daily for 20 days. The weights of the animals and their kidneys, kidney index, glomeruli characteristics, thiobarbituric acid reactive species, antioxidant capacity, kidney function indicators and serum nitrite oxide levels were investigated. Morphine administration significantly improved kidney MDA level, blood urea nitrogen (BUN), creatinine and nitrite oxide levels and decreased glomeruli number and tissue FRAP level compared to the saline group (P < 0.05). The harmine and harmine +  morphine treatments at all doses significantly reduced BUN, kidney MDA level, creatinine, glomerular diameter and nitrite oxide levels and increased the glomeruli number and tissue FRAP level compared to the morphine group (p < 0.05). It seems that harmine administration improved kidney injury induced by morphine in rats.