The use of the age- and sex-specific U.S. population as a control group for analysis of survival in coronary artery disease was assessed. Population-based survival rates were calculated for nonsurgically treated patients evaluated for coronary artery disease at Duke University Medical Center. Survival of the overall group of medically treated patients with significant coronary artery disease was lower than the corresponding age- and sex-specific U.S. population rates. However, survival of patients with significant disease who had normal left ventricular contraction and stable chest pain was similar to the age- and sex-specific population survival rates. Both the observed survival and the population-based survival estimates for patients with normal left ventricular contraction and stable pain were lower than the survival of patients with normal coronary arteriograms. Even after deaths from ischemic heart disease are eliminated from the population rates, survival of patients with normal coronary arteries exceeded the age-and sex-specific population survival. Because of biases inherent in the selection of patients for cardiac catheterization and the presence of other serious diseases in persons in the general population is not an adequate control group for rigorous analysis of the effect of therapy in coronary artery disease.