Abstract Heroin-associated nephropathy (HAN), a complication of intravenous heroin abuse, was initially recognized at Kings County Hospital in Brooklyn, NY, in the early 1970s. Our recent experience indicates that after a steady incidence of new cases of HAN throughout the mid-1980s, a sharp decrease in incidence of new cases occurred starting in 1989. We sought to explore possible explanations for what amounts to disappearance of a previously prevalent disease. By means of retrospective analysis of a hospital-specific registry of new cases of end-stage renal disease (ESRD) at Kings County Hospital in Brooklyn, incidence curves from 1981 through 1993 for new cases of HAN, diabetes-induced renal disease, and human immunodeficiency virus-associated nephropathy were constructed. From hospital computer records, the number of admissions directly related to opioid abuse were extracted and charted. Unpublished surveillance records of the New York State Office of Alcoholism and Substance Abuse Services as well as reports from the New York City Department of Health, Office of AIDS Surveillance and the US Department of Justice Drug Enforcement Administration were used to determine the pattern of change in the prevalence of heroin abuse. Additionally, we used analyses of “street” heroin by the Drug Enforcement Administration to draw curves detailing drug cost and purity in New York City. There were no new cases of ESRD due to HAN for the years 1991 through 1993. The rates for new cases of ESRD due to diabetes and hypertension remained relatively constant throughout this interval. When compared with 1980, the “street” price of heroin in New York City has decreased from $1.43/mg to $0.52/mg. Concurrently, the purity of “street” heroin has increased from 8.0% in 1980 to 60%, with some samples testing as high as 90% in 1992. We theorize that ESRD due to HAN has decreased in incidence because of a progressive improvement in the purity of “street” heroin that eliminates nephrotoxic admixed adulterants.