Female rats were continuously exposed for 3 months to an aerosol containing 50 micrograms/m3 Cadmium-Oxyd and 1.25 mg/m3 Zinc-Oxyd. Our results were compared with those of Prigge (1977), who studied the CdO-toxicity under equal conditions. Inour investigations we studied with clinical and clinico-chemical methods a possible protective effect of ZnO on the Cd-toxicity, given simultanously. A protective effect of ZnO on the Cd-toxicity was evident in out investigations in form of a reduced deposition of Cd in lungs, in livers and kidneys. A reduction of the cadmium-induced hyperplasia of lungs was a remarkable sign for a protective action of Zn. There are some criterions, that Zn, given simultaneously in the studied concentrations, can inhibit the Cd-induced disorder of function in kidneys.