Abstract: This trial was designed to explore the effects of captopril in patients with acute myocardial infarction （AMI ） treated within 36 hours after the onset. Patients received either captopril （C） or placebo （P） 12. 5 mg 3/d to the end of 4weeks. Of the 11345 cases accomplished by over 500 hospitals,5666 were randomly assigned to group C and 5679 to group P.Their baseline clinical characteristics were similar, total mortality in group C （9. 3%） was lower than that in group P（9. 8% ）（P = 0. 36 ）. Causes of death analysis showed that the death from heart failure and ventricular fibrillation decreased by about 15. 5% and 20. 1 % in group C than in control. Subgroup analysis suggested that the mortality of anterior myocardial infarction in group C （9. 5%） was lower than in control （11. 0% ） （P = 0. 06 ）, but mortality of inferior myocardial infarction in group C （7. 5% ） was higher than control （6. 5 % ）（P=0. 3）. Incidence of hypotension in group C increased more than in group P, but no difference was found between the two groups in other side effects. The initial results showed that inpatients with AMI captopril is safe. Although the overall mortality reduced is small,better results in anterior myocardial infarction is worth further investigation. Now, the trial is still ongoing, a data monitoring committee is closely following the trial results.