Background: A novel synthetic antithrombotic drug, cilostazol(Pletaal) has been known to have a potent inhibitory action on platelet aggregation and vasodilating action. Experience in some clinical studies also indicated that administration of cilostazol in diabetic patients was associated with decreased triglyceride levels. To examine the effect of cilostazol on lipid levels in diabetic patients, we performed a multicenter study at 6 centers. Methods: Total 49 patients participaied in this study and they were administered l00 mg of cilostazol twice daily for 12 weeks 9 patients, however, had to discontinue study participation because of adverse events. Results: The mean serum triglyceride and total cholesterol levels were significantly reduced by 28% and by 8% respectively after cilostazol administration for consecutive 12 weeks and that changes appeared at 4 weeks of treatment and were maintained until the end of the study period. There were no significant changes in HDL-cholesterol levels. Because the mean fasting blood glucose and HbAc levels of subjects at 12 weeks were also significantly improved compared to 0 weeks, we selected 20 patients whose blood glucose levels were stable throughout the study period in order to exclude the beneficial effect of glycemic control on lipid profiles. However, significant reduction of triglyceride and total cholesterol levels were still observed in that 20 patients with cilostazol treatment. The score of subjective symptoms(resting pain, numbness, cold sensation) were decreased after cilostazol treatment. The most common side effect was headache, which was noted in l2 patients and most of it occurred during the first few weeks of cilostazol treatment. The assessment of overall improvement of lipid profile, safety and usefulness of dng evaluated by the attending physician were favorable. Conclusion: Above results suggest that cilostazol administration may be helpful in the treatment of diabetic patients with dyslipidemia as well as peripheral vascular disease.