Background: Plasma leptin levels and plasma insulin levels have been found to be elevated in patients with essential hypertension (EH) and have been suggested to be components of the metabolic syndrome. Increased heart rate (HR) may predict the development of EH in normal or borderline-hypertensive individuals. The aim of our study was to test the hypothesis that elevated plasma leptin and insulin levels as well as systolic blood pressure (SBP) and diastolic blood pressure (DBP) and increased resting HR preexist in the healthy offspring of patients with EH. Methods and Results: Twenty-six (12 male, 14 female) healthy offspring of hypertensive patients, mean age 16 ± 2.5 years and body mass index (BMI) of 21.5 ± 2.8 kg/m² (group A), and 30 (14 male, 16 female) healthy offspring of normotensive patients, mean age 17 ± 2.3 years and BMI of 21.9 ± 2.4 kg/m² (group B), were studied. (The two groups were matched for sex, age, and BMI). Mean SBP, DBP, resting HR, plasma leptin, and plasma insulin levels (radioimmunoassay method) were determined in the whole study population. Mean SBP, DBP, and resting HR were significantly higher in group A than in group B (120 ± 12 vs 112 ± 9.5 mm Hg, 77 ± 9 vs 72 ± 7 mm Hg, 79 ± 8 vs 75 ± 5 beats/min, P < .01, P < .05, and P < .05, respectively). Plasma leptin and insulin levels were significantly higher in group A than in group B (9 ± 5.06 vs 5.6 ± 2.5 ng/mL and 20.11 ± 11.3 vs 14.8 ± 5.2 μIU/mL, P < .01 and P < .05, respectively). Conclusions: Our findings support the hypothesis that hyperleptinemia, hyperinsulinemia, and elevated blood pressure and resting HR preexist in the healthy offspring of patients with EH. (Am Heart J 1999;138:922-5.)