The aim of the study is to compare, in coronary artery disease patients, physical activity (PA) assessed with the Dijon Physical Activity Questionnaire (DPAQ) and the true PA objectively measured using an accelerometer. Seventy patients wore an accelerometer (MyWellness Key actimeter) throughout 1 week after a cardiac rehabilitation program that included therapeutic education about regular PA. Patients completed the DPAQ at the end of the week. The mean weekly active energy expenditure was 619.9 [plus or minus] 374.6 kcal, and the mean DPAQ score was 21.3 [plus or minus] 3.1/30 points. There were low but significant correlations between total active energy expenditure and the DPAQ score ([rho]=0.4, P=0.009). There were no correlations between peak power output and total DPAQ score. The DPAQ significantly correlates with objective measures given by the MyWellness Key actimeter. The choice between these tools relies on the clinician's appreciation, taking into account patients' characteristics and goals as well as the cost of the method and availability of the tool. (Contains 2 tables.)