Experiments were performed on white rats with alloxan diabetes and following repeated insulin injections. Zinc distribution was studied histochemically, and the activity of alkaline phosphatase was studied by Gomori's method in the renal tubular cells. Zinc was distributed irregularly in the kidney: its highest concentration was found in the cells of the juxta-glomerular apparatus, in the margin of the cells in the main division of the nephron, in the ascending portion of Henle's loop, and in the tubules of the insertion portion. The highest alkaline phosphatase activity was found in the cells of the main division of the nephron. In alloxan diabetes, the zinc content and the alkaline phosphatase activity showed a sharp decrease, while in the case of repeated insulin injections these indices were observed to rise. A correlation was found between the alkaline phosphatase activity and zinc content in nephron tubules.