The associations between heart rate and death from the cardiovascular diseases (CVD), coronary heart disease (CHD) and sudden death from CHD, along with death from all causes and non-cardiovascular causes, are examined for three groups of middle-aged white males: 1233 men aged 40-59 years followed for 15 years from the Chicago Peoples Gas Company study; 1899 men aged 40-55 years followed for 17 years from the Chicago Western Electric Company study; and 5784 men aged 45-64 years followed an average of five years from the Chicago Heart Association Detection Project in Industry. In univariate analyses, mortality from both cardiovascular and non-cardiovascular causes generally increases with increasing heart rate. In bivariate analyses, using the Cox regression model to control for age, heart rate is significantly related to mortality from all causes in each study, with the associations again due to both cardiovascular and non-cardiovascular causes. In multivariate Cox regression, controlling for age, blood pressure, serum cholesterol, cigarettes smoked per day and relative weight, heart rate is a significant risk factor for sudden CHD death and non-CVD death in two of the three studies, with the association with sudden death being U-shaped in one of the studies. Although heart rate may be an independent risk factor for sudden CHD death, the associations with other CVD death and non-sudden CHD death, in general, appear to be secondary to associations between heart rate and other cardiovascular risk factors.