To characterize the cardiovascular consequences of a history of hypertension in first-degree relatives in normotensive young adults, 72 normotensive (diastolic blood pressure [BP] less than 90 mm Hg) healthy volunteers (age 18 to 30 years) were studied with 2 dimensionally guided M-mode echocardiography, pulsed Doppler echocardiography, and 2-hour automated BP monitoring. Of the 72 subjects, 19 (12 men and 7 women) had a family history of hypertension and were compared with 19 subjects without a family history of hypertension who were matched for systolic BP and gender. There were no detectable differences in 2-hour average BP, left ventricular (LV) mass or wall thickness, or echocardiographic systolic functional indexes between subjects with and without a family history of hypertension. Doppler-derived diastolic functional indexes demonstrated more prominent late diastolic filling in subjects with a family history of hypertension. Late diastolic transmitral flow time and flow velocity integral were greater (132 +/- 24 vs 117 +/- 17 ms, p less than 0.05; and 2.5 +/- 0.7 vs 1.9 +/- 0.5 cm, p less than 0.01, respectively). To measure possible gender-related effects of a family history of hypertension, the men and women were analyzed separately. The 12 men with a family history of hypertension had greater peak late (40 +/- 0.9 vs 31 +/- 0.8 cm/s, p less than 0.02) and ratio of late-to-early (0.64 +/- 0.19 vs 0.46 +/- 0.10, p less than 0.01) transmitral flow velocities and greater late transmitral flow velocity integrals (2.6 +/- 0.8 vs 1.9 +/- 0.5 cm, p less than 0.05) than the matched male control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)