Rosiglitazone is a peroxisome proliferator-activated receptor-γ agonist that has an important role in regulating blood glucose and lipid levels, thus, improving insulin resistance in diabetic patients type II.The present study was to prove the ability of rosiglitazone to reduce platelet function in rats, in comparison to the reducing effect of aspirin. The results proved a significant reduction in platelet aggregation, without affecting platelet count that was nearly equal to that of aspirin, while the combination of both drugs; rosiglitazone and aspirin, resulted in a more significant reduction in aggregation. Therefore, rosiglitazone would be of beneficial effect in reducing risk of cardiovascular disease.