The aim of our study was to evaluate whether initial changes of cardiovascular structure and/or function can be detected in young normotensive subjects with (F+) and without (F-) family history of hypertension. Thirty-two subjects (19 F+, 10 males and 9 females, age range 17-32 years; 13 F-, 6 males and 7 females, age range 19-33 years) were studied. In each subject 24 hours ambulatory blood pressure monitoring, a M-mode, 2d guided and pulsed doppler echocardiogram and postischemic forearm strain gauge plethysmography were performed. The two groups of subjects did not differ for causal systolic and diastolic BP and 24 hours systolic and diastolic ambulatory monitored blood pressure. No differences in LV end-diastolic and end-systolic diameters, as well as in LV wall thickness, and in LV mass index were observed. Systolic functional parameters were also similar in the two groups. In F+ subjects peak early filling velocity was reduced in respect to F- (p < 0.01), peak late filling velocity integral was increased (p < 0.05) and the ratio of peak E/peak A integrals was decreased (p < 0.05). No difference was observed for postischemic forearm blood flow and minimal vascular resistance, taken as an index of arteriolar structural changes as well as intima-media thickness of carotid arteries. In conclusion in this study F+ and F- had similar BP values, LV mass and min VR; differences previously observed in LV mass between F+ and F- may have been due to the presence of different basal levels of BP; in F+ LV diastolic filling, although still in the normal range, shifted early toward the pattern of LV filling usually observed in hypertensive patients.