Aim To investigate the effects of pioglitazone on serum matrix metalloproteinase-9 (MMP-9) and C-reactive protein(CRP) concentration in the elderly patients with acute myocardial infarction(AMI) and type-2 diabetic mellitus. Methods 37 cases of AMI patients accompanied with type-2 diabetic mellitus were divided into two groups according to the administration of pioglitazone previously: pioglitazone group(17 cases) and AMI group(20 cases).23 aged people of health physical examination were enrolled as health control group.The concentrations of serum MMP-9 and CRP were measured in all of the patients. Results The concentration of serum MMP-9 and CRP in AMI group were higher than those in health control group(396.5±67.3 μg/L vs 290.8±75.5 μg/L,8.73±2.59 mg/L vs 3.21±1.11 mg/L).The concentration of serum MMP-9(339.2±79.8 μg/L) and CRP(6.33±2.25 mg/L) in pioglitazone group were lower than those in AMI group. Conclusion Pioglitazone can lower the concentration of serum MMP-9 and CRP level.Pioglitazone has additional cardiovascular effects beside the improvement of insulin resistance.