The existence of a nephropathy secondary to intravenous narcotic use remains a matter of debate. To determine whether heroin use and renal disease are associated, a clinicopathologic and epidemiologic study was undertaken in the Buffalo Standard Metropolitan Statistical Area (Buffalo-SMSA). Over the past 10 years, 23 addicts presented with the nephrotic syndrome and/or renal insufficiency. All patients were black men 18 to 45 years of age. Kidney biopsies performed on 21 patients uniformly showed sclerosing glomerulonephritis. End stage renal disease (ESRD) developd in 15 of these patients. In the epidemiologic evaluation which spanned four and a half years, heroin use was highly correlated with both sclerosing glomerulonephritis and ESRD. A history of intravenous heroin use was found in 26 per cent of the new cases of sclerosing glomerulonephritis and in 13 per cent of the new cases of ESRD in patients aged 18 to 45 years (p less than 0.000001). This investigation confirms the existence of heroin-associated sclerosing glomerulonephritis in black men. Heroin use appears to be a major risk factor for ESRD in the Buffalo-SMSA.