The impact of type A behavior on coronary artery disease was examined in 570 men and 719 women based on 20 years of follow-up in the Framingham Study. A comparison of type A and B persons showed similar levels of systolic blood pressure, total and high density lipoprotein cholesterol and body mass index. Behavioral status also was unrelated to diabetes, cigarette smoking and alcohol intake. Despite similar cardiovascular risk profiles, type A behavior was associated with more than a 2-fold excess risk of angina pectoris, uncomplicated by other symptoms of coronary artery disease (p less than 0.05 for men and p less than 0.01 for women). Type A behavior, however, was not related to an increased risk of myocardial infarction and fatal coronary events. Among the victims of uncomplicated angina, the risk of subsequent coronary morbidity and mortality in both type A and type B men and women increased by more than 4-fold (p less than 0.001). Although the risk was reduced among type A persons, it was not statistically significant. It is concluded that uncomplicated angina pectoris occurs with greater frequency in type A persons than in those who are type B, without explanation by concomitant risk factors. In addition, the prognosis for myocardial infarction and coronary artery disease mortality in angina patients classified as type A is as serious as the prognosis for those who are type B.