The aim of this work was to assess the prevalence and risk factors of obesity in the Balearic Islands' adolescents. A cross-sectional nutritional survey was carried out in the Balearic Islands (2007-2008). A random sample (n 1231) of the adolescent population (12-17 year old) was interviewed. Anthropometric measurements, two non-consecutive 24 h recalls and a general questionnaire incorporating questions related to sociodemographic and lifestyle variables including the physical activity questionnaire were used. The prevalence of overweight was 19.9 % (boys) and 15.5 % (girls), and obesity 12.7 % (boys) and 8.5 % (girls). The main risk factors associated with a higher prevalence of obesity were low parental education level (boys OR: 3.47; 95 % CI: 1.58, 7.62; girls OR: 3.29; 95 % CI: 1.38, 7.89), to skip meals (boys OR: 4.99; 95 % CI: 2.1, 11.54; girls OR: 2.20; 95 % CI: 0.99, 4.89), age (12-13-year-old boys; OR: 2.75; 95 % CI: 1.14, 6.64), attention to mass media (television (TV)+radio; boys OR: 1.50; 95 % CI: 0.81, 2.84; girls OR: 2.06; 95 % CI: 0.91, 4.68), short sleep (boys OR: 3.42; 95 % CI: 0.88, 13.26), low parental socioeconomic status (girls OR: 3.24, 95% CI: 1.04, 10.05 ) and smoking (girls OR: 2.51; 95 % CI: 0.88, 7.13). A programme of action including school healthy education and promotion programmes targeted at parents and adolescents are needed. These programmes may be mainly focused to increase educational level, to make the adolescents to be aware of to skip meals and to smoke are not appropriate methods to reduce the risk of obesity, but the usefulness is to do not eat while watching TV, to sleep 8-10 h/d and to be physically active.