1. A case-control study of the relationship between the regular exposure to hydrocarbons and rapidly progressive glomerulonephritis (GN) was carried out in São Paulo, Brazil. Regular exposure was defined as 1 h or more weekly for 3 consecutive months or longer. We studied 17 patients with rapidly progressive renal failure and biopsy-proven crescentic GN and 34 matched hospital controls. 2. We found an increased risk of rapidly progressive GN associated with exposure to organic solvents (relative risk = 5.00; 95% confidence interval = 1.14 to 22.00). The frequency of exposure to solvents was 52.9% among the patients and 17.7% among the control subjects (P less than 0.05). However, no statistically significant increased risk was detected in those patients who had been exposed to fuels (relative risk = 3.25; 95% confidence interval = 0.76 to 13.89); the proportion of exposure to fuels was 47.1% among the patients and 20.6% among the control subjects. 3. Renal histologic findings suggest that immune complex mediated injury as well as a direct glomerular toxic effect may participate in the pathogenesis of rapidly progressive GN associated with hydrocarbon exposure.