AIM: Higher exercise blood pressure in adults correlates with many cardiometabolic markers. The aim of this study was to investigate the main determinants of longitudinal variations in exercise blood pressure in young athletes. METHODS: A longitudinal retrospective study was conducted on adolescent athletes who underwent at least two sport-related pre-participation screening visits, including exercise testing with a standardized incremental ramp protocol on treadmill. Blood pressure was assessed at rest (SBP_rest), at the 3rd minute of exercise (SBP_3min), and at peak exercise (SBP_peak). Predictors of blood pressure response (i.e., respective changes vs. baseline (Δ)) were determined by multivariate regression models after adjustment for age, sex, follow-up duration, related baseline SBP values, characteristics of sport, and ΔBMI. RESULTS: A total of 351 young athletes (mean age at baseline 13 ± 2 years, 54% boys, average follow-up duration 3.4 ± 2.2 years) were enrolled. BMI increased by 1.5 ± 1.8 kg/m² (p < 0.001) during follow-up. At baseline, mean SBP_rest was 103 ± 14 mmHg, mean SBP_3min 124 ± 18 mmHg, and mean SBPpeak 154 ± 23 mmHg. A significant between-visit increase in SBP_rest (ΔSBP_rest 7.0 ± 17.4 mmHg; p < 0.001), ΔSBP_3min (4.8 ± 11 mmHg, p < 0.001), and ΔSBP_peak (11.7 ± 24 mmHg, p < 0.001) was observed. ΔSBP_3min was significantly predicted by male sex (p < 0.01), baseline BMI (p < 0.01), ΔBMI (p < 0.01), and number of practiced sports (p < 0.05), whereas ΔSBP_peak was positively predicted by male gender (p < 0.01), baseline BMI (p < 0.05), and ΔBMI (p < 0.01) and negatively by baseline resting heart rate (p < 0.01). In a logistic regression model, ΔBMI was the only independent determinant of passing from a lower to an upper quartile of SBP_3min (p < 0.001), while ΔBMI and male sex were independent determinants of moving to a higher quartile of SBP_peak (p < 0.001). CONCLUSIONS: Increase in BMI during development and male sex are independent determinants of the increase in exercise blood pressure, both at light and maximal intensity, in a population of adolescent athletes.