The presence of gold in the kidney of a 58-year-old woman was confirmed by use of ultrastructural and microprobe examinations. A series of animal experiments were performed in which small single doses of gold were administered systemically and intraarticularly in rabbits. Both the colloidal suspension and the soluable salt gold sodium thiomalate (Myochrysine) were used. Selective lesions occurred in the proximal convoluted tubules and the mitochondria appeared to be the target organelle. They contained gold after gold sodium thiomalate but not after colloidal gold.