Levels (microgram/g dry weight) of cadmium (Cd), zinc (Zn) and copper (Cu) were determined in kidneys with renal cell carcinoma from 20 male and 11 female patients. Autopsied kidneys from nine males and eight females who had died of nonmalignant diseases were used as controls. The mean levels in cortex of Cd was in cases 103.2 and in controls 79.9 (not significantly different). For non-smoking cases, mean level of Cd in cortex was somewhat lower than in the controls. No significant differences were found between cases and controls for Cd levels in the medulla. Zn in cortex was significantly lower in the cases aged > or = 69 years (mean 182.0) than in the corresponding controls (mean 237.6). Zn in medulla was significantly lower in all cases (mean 103.5) than in controls (mean 162.2). The mean level of Cu in the medulla in cases was 10.7 and in controls 13.0 (P = 0.05). No differences were found for Cu levels in cortex.