Oxygen consumption (QO2), respiratory quotient (RQ) and gluconeogenesis of rat kidney cortex slices were determined (Warburg technique). QO2 was not influenced by 0.01 mM CdCl2 in the incubation medium (no exogenous substrate added), 0.1 mM, 1mM and 10 mM, respectively, reduced QO2 by 43%, 45% and 68%. In the presence of 8 mM glucose, 10 mM acetate or 5 mM butyrate, 1 mM Cd resulted in a decrease in QO2 by about 50% each. Addition of 20 g/l albumine to the medium abolished this effect of cadmium. RQ was not influenced by a mM Cd, both without and with 8 mM glucose in the medium. Glucose production from 7 mM pyruvate or 5 mM glutaminate in slices from fed and starving rats was reduced by 1 mM Cd to half the value found in controls.