Streptozotocin (SZ) was inoculated intraperitoneally to male and female mice of ICR and BALB/c strains in a different way of administration (A: single injection and B consecutive 5 days-injection) and subacute renal changes were examined light and electron microscopically 8 weeks after SZ-administration. The following changes were detected: (1) reduction in the rate of male-type Bowman's capsules in male mice, (2) karyocytomegaly of proximal tubular epithelial cells, and (3) dilation of distal tubules Tubular changes were detected with high incidence in A (males and females) and B groups (males) of ICR strain.