We identified the early and late prognostic factors of acute myocardial infarction, and evaluated the clinical differences and the prognosis between Q-wave myocardial infarction and non-Q wave myocardial infarction. Total 146 patients who were managed from Jan 1987 to Aug. 1989 at hallym University hospital were evaluated. According to the presence or absence of Q wave on electrocardiogram, the patients were divided into two groups : a Q wave myocardial infarction group(QMI) and a non-Q wave myocardial infarction group (NQMI). Among 146 patients 109 patients(74.7%) had QMI and 37 patients(25.3%) had NQNI. The mean age, male to female ratio and serum cholesterol level were similar in both groups. But peak level of CPK was significantly higher in the QMI group than that in the NQMI group(P<0.01). Left ventricular end-systolic dimension and ratio of left ventricular dimension to wall thickness in the QMI group were significantly higher than that in the NQMI group(P<0.01). There were no significant differences between two groups in the incidences of mortality, postinfarction angina and re-infarction. During the in-hospital period female gender, old age(more than 60 years), Killip class at admission, early reinfarction and a history of hypertension were significant prognostic factors. main causes of death during the in-hospital period were ventricular tachyarrthymia, heart failure and cardiogenic shock. The incidences of mortality, heart failure and post-infarction angina during a mean follow-up period of 14 months (6~30months) were same in the two groups. The late prognostic factors were old age(more than 60 years), Killip class at admission, heart failure occured during follow-up period(P<0.001) and a history of diabetes mellitus(P<0.05). The patients with late postinfarction angina had more dilated left ventricular end-systolic demension(P<0.05) and lower fractional shortening(P<0.01) than those of patients without late postinfraction angina. There were no significant difference in long term survival rate between QMI group and NQMI group. Further prospective study should be performed to clarify the short and long term prognosis in patients with acute myocardial infarction treated by reperfusion.