Limited studies were found to compare the physical activity (PA) levels between different countries. Since different PA measurements and definitions were adopted by different countries, cross-cultural comparison becomes difficult. The purpose of the present study was, using the same PA measurement, to compare the PA level of children between three major metropolitan cities in Asia. A total of 6,685 junior high school children, age 12-15 years old, were recruited randomly from Hong Kong (N=3,276), Seoul (N=1,332), and Tokyo (N=2,077). Informed consents were obtained from participated schools and parents. All children completed the same PA questionnaire which was an activity rating scale (PAR) ranging from 0-10 developed by Hui (2001). The PAR described various activity levels in a 0-10 continuum, with "0" being the least active and "10" the most active. The PAR asked about the weekly average activity level in the past year, with the consideration of a combination of frequency, duration, and intensity of the activity. PA level of children was further classified into groups of either "sedentary" (PAR=0-2), "somewhat active" (PAR=3-6), or "active" (7-10) for analysis. Results from 2-way (gender x cities) ANOVA on PAR revealed that both main effects and interaction effect were significant (p<.001). In all three cities, PAR of boys was greater than girls. The mean PAR of Tokyo was the greatest (6.87), followed by Hong Kong (4.88) and Seoul (3.69). The difference in PAR between boys and girls was different between the three cities. When another 2-way (age x cities) ANOVA was conducted separately for boys and girls, similar significant findings were obtained (p<.001). Regardless of gender, the PAR dropped significantly from age 12 to 15, except the PAR for girls in Hong Kong and Seoul remained fairly consistent. The trends of change in PAR with age were different between the three cities. More surprisingly, a very high portion (64.6%) of Tokyo°¦s children was classified as "active" enough to derive health benefits, whereas only 28.9% in Hong Kong and 14.1% in Seoul were classified as "active". These results suggested that although the three Asia metropolitan cities share similar ethical origin and urbanization, the PA levels and patterns are very different and are functions of age and gender. Reasons for the high active proportion in Tokyo are not clear and may probably related to the strong sports culture and P.E. curriculum. Further research is suggested to investigate factors contribute to these PA differences.Keyword(s): health promotion, international issues, physical activity