Background. High blood pressure in adults is directly correlated with increased risk of cardiovascular diseases. Hypertension in childhood and adolescence could be considered among the major causes of this problem in adults. This study aimed to investigate the factors associated with hypertension among the adolescents of Jahrom city in Iran and also standard percentiles of blood pressure were estimated for this group. Methods. In this community-based cross-sectional study 983 high school students from different areas of the city were included using a multistage random cluster sampling method in 2014. Blood pressure, weight, and height of each student measured using standard methods. Data were analyzed by statistical software SPSS 16. Results. In total, 498 male and 454 female students were included in this study. Average systolic blood pressure of students was 110.27 mmHg with a variation range of 80.6-151.3. Average diastolic blood pressure was 71.76 mmHg with the variation range of 49.3-105. Results of this study indicated that there was a significant relationship between gender, body mass index, and parental education level with systolic and diastolic blood pressure of the students (P < 0.05). Conclusions. Body mass index was one of the most important changeable factors associated with blood pressure in adolescents. Paying attention to this factor in adolescence could be effective in prevention of cardiovascular diseases in adulthood.