Sarpogrelate, a selective 5-HT(2) receptor antagonist, is known to have a significant effect on antiplatelet action. This study was a double-blinded, randomized, paralleled multicenter trial to compare the effects of sarpogrelate and aspirin on preventing macrovascular complications in patients with type 2 diabetes. The subjects were randomly assigned to either the sarpogrelateor the aspirin group. The baseline parameters for macrovascular complications, such as intima media thickness (IMT), ankle-brachial index (ABI), IL-6, serotonin, adiponectin, and hsCRP, were measured before drug administration. Changes were compared at 6 and 12 months after the administration of each drug. A total of 127 subjects (63 in the sarpogrelate group and 64 in the aspirin group) were pooled during the study period. No significant differences were found in baseline IMT or in other predictors of macrovascular complications. The mean IMT increased in both groups after 12 months, but there was no significant difference between the two groups. No significant change was found in the other predictors of macrovascular complications nor in the incidence of drug-related adverse events between the two groups. During the study period, no significant differences were found between the sarpogrelate group and aspirin group in the clinical indices or in the safety of the subjects related to macrovascular complications. This suggests that sarpogrelate may be clinically useful for the primary prevention of macrovascular complications in patients with type 2 diabetes.