In 139 patients with preexisting abnormal renal function (serum creatinine level of 2.0 mg/dL or greater) undergoing cardiac angiography (141 examinations), the incidence of contrast nephropathy, defined as a 1 mg/dL or greater rise in serum creatinine, was 23% (95% confidence interval, 17% to 30%). Stepwise logistic regression analysis showed that contrast nephropathy was independently associated with class IV heart failure with low cardiac output (71% incidence in this subgroup; p less than 0.0001), multiple radiocontrast studies within 72 hours (50%; p = 0.002), dose of radiocontrast administered (p = 0.009), and insulin-dependent diabetes mellitus (44%; p = 0.007). Age, hypertension, and hyperuricemia were not associated. In patients without low cardiac output, other radiocontrast tests, or insulin-dependent diabetes mellitus, there was a 2% incidence of contrast nephropathy in those who received less than 125 mL radiocontrast and a 19% incidence in those who received 125 mL or greater.