Background: With a high prevalence of non communicable diseases and its risk factors among the Saudi Arabian population, the present study was conducted to determine the levels and pattern of physical activity behavior of the youth with reference to their parents’ diabetes/hypertension status.Methods: A cross sectional study was performed in higher secondary schools and university. Multistage cluster random sampling technique was used to obtain a sample of 450 subjects aged 15-25 years. All types of physical activity performed in daily routine were recorded using a validated questionnaire. Data was reported as mean or median physical activity hours for normal and skewed data and corresponding test of significance was applied.Results: There was a high prevalence of sedentary behavior among the overall population (76.5 median hours per week). Female gender (p<0.002) and transition to university (p<0.000) showed increased sedentarism. Subjects whose both parents were affected with diabetes showed least sedentary behavior [70 (19) mean hours per week] and higher levels of moderate (2.25 median hours per week; p<0.025) and strenuous physical activity (1.25 median hours per week; p<0.034). Maternal diabetes also showed significant influence in improving the physical activity of the subjects. Presence of maternal history of hypertension or both parents affected by hypertension did not make any significant impact on the physical activity pattern of their offsprings.Conclusions: Increased physical activity was observed only among those who had family history of diabetes. Otherwise the normal population showed a typical sedentary lifestyle reflecting on the questionable effectiveness of national programs on physical activity.