Literature on the prevalence of physical activity in Asian countries is limited, despite evidence of increasing rates of sedentary-related disease such as obesity and diabetes. It is important to establish nationally representative data in countries such as Taiwan to set up levels and patterns of activity and to inform health policy. Unpublished data from four cross-sectional nationally representative surveys comprising 29,226 people aged 20 and older were analyzed. We explored the population prevalence of meeting national recommendations for health, examined temporal change across a 4-year period, and attempted comparisons with neighboring Asian and selected westernized countries. Logistic regression analysis provided adjusted odds ratios of physical activity engagement for several demographic variables. Around 14% of Taiwanese adults met national recommendations. Similar to other Asian countries, but in contrast to declines with age seen in western populations, people aged 45 and older were more likely to be active than younger people. High-risk groups for inactivity were those aged 20-44 with limited formal education and in paid employment. Overall prevalence in leisure-time physical activity was low. There is scope to increase active leisure for improving health, particularly among younger adults.