Objective. To assess the association between the built environment and physical fitness and physical activity in adolescents. Methods. The study included 3528 adolescents, aged 12.5-17.5 years, who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study. The health-related physical fitness components were assessed using the physical fitness tests. Participants wore a uniaxial accelerometer (ActiGraph (R)) for 7 days to measure physical activity. A specific questionnaire addressing the built environment was used. Potential confounding factors including age, gender, body mass index, body composition, pubertal status, smoking, educational level of parents, and socioeconomic status were analyzed using backward stepwise linear regression analysis. Results. Heavy traffic in the neighborhood was the strongest factor negatively associated with both physical fitness and physical activity (both P < 0.05). Conversely, a secure bicycling or walking route from home to school was positively associated with various components of physical fitness and physical activity (P < 0.01). Outdoor fields and gymnasiums near home were also associated with better physical fitness (P < 0.01), but not with physical activity. Conclusions. A favorable built environment may contribute to health-related physical fitness and physical activity of adolescents and should be considered in future interventions and health promotion strategies. (C) 2013 Elsevier Inc. All rights reserved.