The recent and significant increase of cocaine abuse has emerged as a major public health problems. Cocaine abuse is frequently associated with multiorganic lesions, including renal failure. We report the light-microscopic features of the progression of renal lesions produced by chronic cocaine administration in rats. Male Wistar rats weighing 225-250 g were used. Twenty eight rats received an aqueous solution of cocaine hydrochloride (30 mg/kg/day i.p.) daily, while 28 control rats were injected i.p. daily with a saline solution. Rats from both groups were sacrificed after 7, 15, 30, 45, 60, 75 and 90 days of treatment. The histopathological study showed early changes on day 15, with damage to glomerular capillary walls and swelling of tubular epithelium, and lesions progressed to 90 days with development of glomerular atrophy and sclerosis. The tubular epithelial cells were necrotic and sloughed, and the lumen of papillary ducts contained destroyed red blood cell (RBC) casts. The interstitium had numerous foci of necrosis and haemorrhage. The results show that chronic treatment with cocaine in rats produce severe lesions both to glomerular, interstitium and tubular cells.