The effect of habitual leisure time physical activity (LTPA) on the 10.5-year total and cause-specific mortality rates was studied in 12,138 middle-aged men at high risk for coronary heart disease (CHD) who participated in the MRFIT. The level of LTPA as determined by the Minnesota questionnaire was inversely related to rate of death from cardiovascular (CVD), coronary heart disease (CHD), and all-causes, but was unrelated to the cancer death rate. The least active men (LTPA tertile 1) had excess mortality rates of 22%, 27%, and 15% for CVD, CHD, all-causes, respectively, as compared to more active men in the middle third (tertile 2). Additional LTPA (tertile 3) was not associated with further attenuation of mortality rates. Proportional hazards regression analysis only slightly weakened risk differentials. This study supports previous observations that regular LTPA is associated with a reduced rate of CVD mortality, independent of other risk factor levels.