- Summary Background There has been a significant increase in the prevalence of obesity among children and adolescents over the last few decades. Obesity is associated with significant psychosocial and physical morbidity. Objective The aim of this study was to define the prevalence of obesity and associated morbidity, including type 2 diabetes and hypertension, among 17-year-old adolescents. A comparison between the morbidity patterns of females and males was also performed. Design All 17-year-old Israeli nationals are obliged by law to present at the Israel Defence Forces recruiting office for a medical examination, with the exception of orthodox religious and Arabic adolescents. Height and weight are measured and classified, and a trained specialist evaluates those with suspected associated diseases. The level of education is also recorded. Results Our survey included 76,732 adolescents, 32,402(42.2%) females and 44,330(57.8%) males. The prevalence of obesity and morbid obesity among 17-year-old Israeli conscripts was 4.1% in males and 3.3% in females. The prevalence of borderline overweight was 12.4% in males and 11.4% in females. The prevalence of hypertension and type 2 diabetes was significantly higher among conscripts with BMI>30 kg/m 2 in both genders. There was also a significantly higher prevalence of hypertension and type 2 diabetes in males compared with females( P 30 kg/m 2 . There was no significant difference among the male conscripts. Conclusions This study found a relatively low prevalence of obesity among 17-year-old Israeli conscripts, but an alarmingly high prevalence of borderline overweight. Obesity was correlated with a higher prevalence of hypertension and type 2 diabetes, and a lower level of education. There was a significant difference between genders in the prevalence of hypertension and type 2 diabetes, and this should be further investigated. These data call for the creation of new education programmes on the prevention of overweight among children and adolescents.