Since the advent of antiarrhythmic therapy, most deaths following myocardial infarction have resulted from heart failure or shock due to loss of functioning muscle. To study the influence of the location of these infarcts, all cases of MI in Paterson, New Jersey residents were traced in 1974 to hospitals in and around the city by using the 1970 census. Of 157 documented MIs analyzed, 18 (11.5%) were subendocardial, 78 (49.7%) occurred in the anterior wall, and 61 (38.9%) in the inferior wall. The three groups did not differ with respect to age, sex, race, or history or electrocardiographic evidence of previous MI. The clinical characteristics were also similar. Smoking was the most frequent risk factor. Hypertension and diabetes were more prevalent than hyperlipidemia (P < 0.05). These risk factors were distributed similarly in the three groups. Except for lactic dehydrogenase, which was significantly higher in the patients with transmural infarctions, serum glutamic-oxaloacetic transaminase, and creatinine phosphokinase values were similar in the three groups. Complications and mortality from MI were also similar in the three groups. Aside from older age and the presence of diabetes, which adversely influenced the mortality, there were no differences between the survivors of the three groups and those who died. Although subendocardial MI was less frequent, once MI occurs, the location does not influence the outcome. The clinical features, complications and mortality are essentially similar. © 1979, Sage Publications. All rights reserved.