Wistar rats were exposed to trinitrotoluene (TNT, 200 mg/kg/d x 6 d/wk) for 6 weeks, and a 2-week recovery period was continued after treatment. After initiation of TNT exposure, zinc and copper concentrations in rat testes, liver and serum, and serum caeruloplasmin activity were assayed every 2 weeks. Testicular size and zinc concentrations were decreased throughout the exposure and recovery periods. After 6 weeks of TNT exposure, rat testicular copper and serum zinc concentrations were significantly decreased and increased, respectively. The activities of caeruloplasmin were decreased after 4 and 6 weeks of exposure. Liver zinc and copper concentrations and serum copper concentrations had not changed significantly in rats throughout the exposure and recovery periods. Copper concentration in hair samples from TNT-exposed workers was lower than that in control workers, but zinc content was significantly increased compared with that in control workers.