In a consecutive series of 62 hypertensive elderly subjects, the authors studied the relation of blood pressure circadian variations with echocardiographic parameters of left ventricular (LV) hypertrophy. All the subjects were submitted to an ambulatory blood pressure monitoring (ABPM) and to B- and M-mode echocardiography. In the elderly hypertensive group, LV mass index (LVMI) was more strongly related to twenty-four-hour, daytime and nighttime systolic ambulatory blood pressure (r = 0.52, r = 0.37, r = 0.51) than diastolic ambulatory blood pressures were (r = 0.32, r = 0.18, r = 0.33). Casual systolic and diastolic blood pressure (CBP) was found more weakly related to LVMI than ambulatory blood pressures were (r = 0.35, r = 0.26). Elderly hypertensive subjects were divided into two subgroups in relation to the presence (group 1) or absence (group 2) of blood pressure nocturnal decline. No differences were found between these two subgroups in regard to: casual blood pressure values, ambulatory blood pressures in the diurnal period, sex, body surface area, height, weight, and age. LVMIs were computed in all three groups and showed the following results: 89.32 +/- 19.76 in elderly normotensives, 91.21 +/- 31.32 in group 1, and 99.80 +/- 18.21 in group 2. Echocardiographic parameters of LV dimensions and LVMIs were different in group 1 and 2. An inverse correlation, statistically significant, was observed between LVMIs and the nocturnal blood pressure reduction (systolic: r = -0.36, P < 0.05; diastolic: r = -0.29, P < 0.05). These results suggest an association between a smaller LV mass and nocturnal blood pressure decline in elderly hypertensive patients.