Nowadays, a variety of techniques have been used to assess physical activity patterns in children. One of these techniques is the questionnaire method. Therefore, 220 Saudi boys between the ages of 7 and 12 years have been subjected to a thorough assessment of physical activity by the questionnaire method. Comparison of physical activity levels between heart rate telemetry and the questionnaire method was also made. Results of the study indicated that parents were overestimating their children's activity levels. The most frequently practiced activities were soccer, swimming and cycling. Only 24% of the sample indicated that they spend more than five hours a week in physical activities. The percentage of children's television viewing was thought to be low (75% spend less than 5 hours a week in front of a TV set). A high percentage of the parents (98%) believe in the importance of physical activity for their children. lt was also found that parent's physical activity levels were moderately correlated (r = ,20; p = ,002) with children's physical activity levels. A moderate correlation (r = ,34; p = ,001) was found between physical activity levels by the questionnaire method and VO2 max of the children. Finally, the most striking result was that physical activity levels assessed by parents were not correlated with heart rate telemetry.