A simple, five-question risk test for coronary heart disease (CHD) is presented. The test allows a person to estimate his or her relative risk of CHD, based on answers to questions on smoking habits, history of diagnosis and treatment for high blood pressure, weight, pulse rate and family history of heart disease. The scoring system, developed from the 17-year CHD mortality study of 1899 white males age 40-55 years from the Chicago Western Electric Company study, is applied to the men of that study and predictively to 1158 white men age 40-59 years followed 15 years in the Chicago Peoples Gas Company study. In these two studies, the men with the highest quintile of risk scores had more than four times the observed numbers of CHD deaths as the men in the lowest quintile of risk scores. In addition, a test that uses actual blood pressure instead of treatment status, and includes serum cholesterol level, is also presented for use in cases where the values of these variables are available. Although the scoring systems for these tests are based on the mortality experience of middle-aged white males, the tests should have approximate validity for all age-sex-race groups because the scores are a measure of relative risk.