Purpose: Although there is substantial evidence that physical activity reduces a person's risk of cardiovascular disease (CVD), few of these studies have included African Americans. The studies that have included African Americans offer inconclusive evidence on the association, and none studied heart failure separately. We used data from the Atherosclerosis Risk in Communities study cohort to examine, in African Americans, the association of physical activity with the incidence of CVD and its major components - stroke, heart failure, and CHD. Methods: Participants age 45-64 yr (3707 African Americans and, for comparison, 10,018 Caucasians) had physical activity assessed via questionnaire in 1987 and were followed for incident CVD (n = 1039) through 2008. Results: After adjustment for potential confounders, physical activity was inversely related to CVD, heart failure, and CHD incidence in both races (P values for trend <0.0001), and with stroke in African Americans. Hazard ratios (95% confidence intervals) for CVD for each higher physical activity category were similar by race: 1.0, 0.65 (0.56-0.75), and 0.59 (0.49-0.71) for African Americans and 1.0, 0.74 (0.66-0.83), and 0.67 (0.59-0.75) for Caucasians (P value for interaction = 0.38). Conclusions: Our findings reinforce recommendations that regular physical activity is important for CVD risk reduction in African Americans as well as Caucasians and support the idea that some physical activity is better than none.