To determine the level of daily physical activity routinely performed by patients with congestive heart failure (CHF) and the ability of clinical and laboratory assessments of function to predict peak daily activity levels, 45 patients with CHF were evaluated in the laboratory and during 2 days of usual activity. Subjects performed symptom-limited treadmill exercise tests with respiratory gas analysis and wore a Vitalog activity monitor with continuous measurement of heart rate and body motion. Mean maximal oxygen uptake for this sample was 16.8 ml/kg/min. Peak daily physical activity involved walking on a flat surface (44%), or general activities (housework/yardwork, 42%). Most subjects were asymptomatic (49%) during daily physical activity, 22% noted dyspnea, 16% fatigue and 13% sore muscles/joints. Perceived intensity of peak daily physical activity (mean = 4.19, SD = 2.21) was similar to perceived exertion (mean = 3.73, SD = 1.37) reported at ventilatory threshold measured during treadmill exercise testing. Subjects may control their peak daily physical activity to minimize symptoms experienced. It was further observed that current methods of assessing functional capacity in these patients were inadequate for estimating the peak level of daily activity. In conclusion, daily physical activity levels are low in patients with congestive heart failure and a gap exists between exercise capacity and actual performance of daily physical activity.