Between July 1974 and May 1979, 19,153 non-randomized patients without prior cardiac surgery and with chest pain were studied angiographically and enrolled in the Coronary Artery Surgery Study (CASS). The primary question addressed by this paper is: for fixed levels of coronary artery disease, are the presence and severity of angina pectoris greater for older than for younger patients? For those with the same extent of disease, older patients were more likely to have angina and to exhibit more severe symptoms. After adjustment for covariates using logistic regression analysis, age was found to be an important, independent predictor of the presence and severity of angina. There are many possible explanations for these findings, although physiologic factors related to aging, the disease process, and deconditioning associated with an increased sedentary life style seem most reasonable. Another possibility has to do with referral patterns for study and the prevalence of angina in the different age groups.