The urinary concentration of cadmium, copper and zinc was determined in 12 male workers who had been engaged in welding work with cadmiumcontaining silver solder. Sephadex chromatographic analysis for these urinary metals was performed in two workers suspected of suffering cadmium-induced renal injury. The mean values of the cadmium, copper and zinc concentrations in the urine of the welders were about 26, 2.4 and 2.6 times the control values, respectively. A linear relationship was obtained between the urinary concentrations of cadmium and both copper and zinc. The chromatographic distribution of these urinary metals in the welders showed that the metallothionein fraction contained cadmium and copper, but not zinc. The copper content of this fraction was much larger than the cadmium content. The cadmium and copper in this fraction represented about 6% and 10% of the respective total amounts of these metals in the urine. The remaining cadmium and copper were recovered from the high molecular weight protein fraction and low molecular weight nonprotein fraction. The urinary zinc was recovered from both these fractions. The zinc in the latter fraction represented 85% of the total urinary zinc. The present results suggest that cadmium accumulation affects the excretion of copper and zinc in the urine, and that the urinary excretion of metallothionein containing cadmiun as well as copper may be involved in cadmium induced renal injury.