1. The present study was undertaken to compare the effects of beraprost sodium (BPS), a stable prostaglandin I2 analog, with prostaglandin E1 (PGE1) on the skin blood flow in anesthesized diabetic rats and anesthetized dogs. 2. In anesthetized diabetic rats, BPS, but not PGE1, caused a dose-dependent and significant increase in femoral skin blood flow. 3. In anesthetized dogs, PGE1 significantly increased femoral arterial blood flow than BPS. However, BPS significantly increased in-step skin blood flow than PGE1. 4. The above data suggest that BPS may be clinically useful for the treatment of circulatory insufficiency of lower extremities in diabetic patients.