We examined 174 subjects (82 men and 92 women) with essential hypertension to determine whether gender played an important role in the association of blood pressure (BP) familial disposition, and hypertension. To evaluate the salt sensitivity of BP, we measured changes in blood pressure after restricting salt intake from about 15 g/day to less than 3 g/day. The familial disposition to hypertension was categorized into four groups according to the presence or absence of hypertension in the father, mother, and siblings. If none, one, two, or three family members had hypertension, they were assigned the FH(-), FH(+), FH(++), and FH( ) groups, respectively. Only in women did the FH(-) group show a significantly smaller blood pressure reduction than that of the other groups. The mean BP reduction in the four groups was 4.1 +/- 1.9, 8.5 +/- 1.1, 10.1 +/- 1.5, and 11.2 +/- 2.8 mm Hg (mean +/- SEM), respectively. This difference in BP reduction was not observed in men. Multiple regression analysis, using percent changes in mean BP as the dependent variable and other factors as independent variables, also showed a significant partial correlation coefficient for familial disposition to hypertension only in women. Thus, the relationship between salt sensitivity and familial disposition to hypertension differed according to gender. This difference may provide an important insight into the hereditary nature of hypertension.