It is well established that physical inactivity in adults is associated with increased mortality and morbidity. Whether daily physical activity level is related to risk factors for cardiovascular disease (CVD) in children has been debated. Furthermore, objective data on the habitual daily physical activity in children have at large been scarce in the literature. The main reason for this is the fact that daily physical activity is very difficult to measure in children. In recent years, a new device, the accelerometer, has emerged as a frequently used instrument for the measurement of daily physical activity. This review summarizes recently published studies that have used accelerometers to measure daily physical activity in children and related activity data to known risk factors for CVD.