To determine if additive or synergistic toxic effects would occur, adult male rats were exposed orally to lead carbonat e (2,000 mg/kg) for 9 days before trichloroethylen e (TCE), 2,000 mg/kg, was given concurrentl y for an additional 7 days. Comparisons were made with groups of vehicle-treated rats and rats given only lead or only TCE. Potential neurotoxicity was evaluated by using the Functional Observationa l Battery (FOB) recommended for neurotoxicity screening. Rats were sacri ced on day 16, and brain, testes, spleen, kidney/adrenals, heart, and liver weighed and observed for pathological changes. Results of the FOB indicated that lead carbonate was more responsible than TCE for changes observed. Additive or synergistic neurotoxicities were not noted. Histological examination of the kidney from lead-treated rats revealed inclusions, an increased incidence of coagulated proteins, and tubular dilation that was generally more severe in the medullary segments. Gastric and testicular necrosis were found in rats given lead carbonate both with and without TCE (15/20 and 6/20 treated, respectively). The results suggest that, even when given concurrently, the toxicities of lead carbonate and TCE are expressed only as though one toxicant was given.