The aim was to determine differences in anthropometric measurements, dietary habits, serum lipid and glucose levels in relation to high blood pressure (BP) among adolescent boys and girls in Croatia. The specific aim was to determine the effect of dietary habits and lifestyle on high BP in adolescents according to sex. The study included 260 (68.2%) adolescent girls and 121 (31.8%) boys with anthropometric data obtained (without missing values) from 246 girls and 111 boys. Participants answered questions from the questionnaire and anthropometric BP and blood test values were obtained. Non-parametric tests were used in analyses of reference intervals of systolic and diastolic BP in adolescent boys and girls according to age. High BP was defined as ≥90 th percentile for adolescent girls and boys, with a value of ≥135/87.5 mm Hg. Mann-Whitney U test was used to analyze differences in anthropometric and laboratory values between the groups of girls and boys with high (≤90 th percentile) and normal BP. Increase in systolic and diastolic BP was noted in the adolescents. In girls, BP values showed a decreasing systolic and increasing diastolic BP trend with age. Girls with high BP had a significantly higher body mass index (BMI) (p=0.020), waist circumference (WC) (p=0.002), waist-to-height ratio (WHtR) (p=0.016), waist-to-hip ratio (WHR) (p=0.043), hip circumference (HC) (p=0.015), triglyceride (TG) levels (p=0.021), higher prevalence of unhealthy diet at school breakfast (p=0.008) and lower prevalence of eating fish (p=0.02). Boys with high BP had a significantly higher BMI (p=0.045), WC (p=0.004), WHtR (p=0.017), WHR (p=0.022) and higher prevalence of eating meat products (p=0.015). Effective health interventions are needed to reduce the risk of developing cardiovascular diseases and preventing age-related illness.