Hypertension tracks throughout childhood into adulthood. Elevated aldosterone in the setting of low renin predicts incident hypertension in normotensive adults, but the relationship is unclear in adolescents and young adults. To explore this relationship, we analyzed data from the offsprings (Gen2) of women enrolled during pregnancy into the Raine Study (population-based birth cohort), who had blood pressure (BP) measurements and blood samples at age 17 years (N=871) and age 27 years (N=758). At 17 years, females had similar median aldosterone levels (349 versus 346 pmol/L) but significantly lower direct renin concentration (20.6 versus 25.7 mU/L) and thus a higher aldosterone-to-renin ratio (ARR; 18.3 versus 13.5) compared with males. However, females had lower systolic BP (109 versus 118 mm Hg) versus males. A significant association between ARR and systolic BP was detected in 17 years males when adjusted for alcohol consumption, physical activity, and body mass index. This was true whether the ARR was expressed as a continuous variable (β-coefficient 0.1, P =0.009) or categorical variable (highest versus lowest quartile, β-coefficient 3.15, P =0.003). No such correlation was observed in females at 17 years. However, the ARR at 17 years was significantly associated with both systolic (β-coefficient 0.15, P =0.009) and diastolic BP (β-coefficient 0.14, P =0.003) at 27 years among females, but not males. The sexually dimorphic relationship between the ARR and BP in 17 and 27 years participants suggests that the ARR, calculated from the plasma aldosterone concentration and direct renin concentration, could be a useful tool for BP prediction and assessment in young people, but require sex-specific interpretation.