Peripheral vascular disease is a common complication in diabetes mellitus. Accelerated atherosclerosis leading to impaired circulation in the legs is one of the most important causes of gangrene and amputation. In previous studies, a critically low systolic ankle and toe blood pressure has been shown to indicate a high probability for development of diabetic gangrene. The aim of the presint prospective study was to report the results of the treatment of 200 mg/day Cilostazol which has a vasodilating and antithrombotic action in 30 diabetic patients with peritheral vascular disease. The results were as follows: 1) The score of resting pain, numbness, cold sensation, claudication and granuloma were significantly decreased after Cilostazol treatment for 8 weeks.2) The ankle pressure index was increased from 0.92±0.21 to 0.96±0.15, after Cilostazol treatment for 8 weeks. The score of arterial palpation and dopler wave were markely improved in both groups after Cilostazol treatment. 3) Facial flushing, headache and chest pain were noted, but geadache and chest pain were dissappeared spontaneously during Cilostazol administration 4) The assessement of overall safety of the drug evaluated by the attending-physician bases on the assessement of "safe" and "almost safe" amounted to 96.7%. The assessment of overall improvement of the deasease made by the attending physician based on the improvement of resting pain, cold sensation, claudication, numbness, ulcer and granuloma indicated that the percent improvement based on the combined assessments of "markedly improved", "improved" and "slightly improved" amounted to 86.6% 5) Fasting blood sugar, postprandial 2 hour sugar and HbAlc levels were significantly decreased after Cilostazol administration.