The objectives of this investigation were to study the effects of cadmium toxicity on the kidney at chronic and acute dosing and to determine whether there is a release of the tubular enzyme glutamyl transpeptidase (GT) into the urine. The dosing regimen was established in such a way that after four weeks, the low chronic group had received about the same total amount of cadmium as the low acute group, and the high chronic group received about the same total amount of cadmium as the high acute group. Kidney cadmium concentrations in the acutely dosed animals reached higher levels than in the corresponding chronically dosed groups. Zinc levels remained essentially the same for all dosed groups. Cadmium levels in urine, for all groups, throughout the experiment, were less than 0.05 microgram/ml. Both acutely dosed groups gained substantially less weight than the chronically dosed groups. Acutely exposed animals showed greatly depressed urinary protein excretion for all days measured. Chronically exposed animals showed essentially the same protein excretion as control animals. Urinary GT levels were significantly decreased in acutely dosed animals from day 3 to 21. Chronically dosed animals also showed diminished GT levels after day 7.