To assess the association between regular physical activity in adolescence and leisure-time physical activity in adulthood, with emphasis on gender differences among the urban population of Tehran, Iran. A population- based cross-sectional study was carried out on an urban population of 200 persons under the age of 20 years and above 55 years via cluster sampling in local zone of Tehran (3area), in 2008.We interviewed them by IPAQ (International Physical Activity Questionnaire) for evaluated leisure-time physical activity levels. Data on adolescent physical activity were based on subjects’ recall. Of 200 subjects interviewed, 67% were classified as adequately active, and 23.5% reported regular physical activity in adolescence. Subjects who engaged in regular physical activity during adolescence were more likely to be adequately active in adulthood (adjust prevalence ratio: 0.225, 95%, 667.1). This effect was stronger in women (adjust prevalence ratio: 0.225, 95%, 1.321) than men (adjust prevalence ratio: 0.225, 95%, 1.3333). Furthermore, physical inactivity was more prevalent in the higher socioeconomic group. Promoting physical activity in school age may be a successful intervention against the epidemic of adult inactivity. Although women were less likely to report regular physical activity in adolescence, the effect of this experience on adult behavior was stronger than men specially in employment. (64.4% in men and 57.8% in women). Also, the level of physical activity in urban population of 3rd area of Tehran was low. High risk is associated with employment, retirement, high socioeconomic class and higher levels of education.