The objective of this study was to assess the value of two substitutes for ambulatory blood pressure (BP) monitoring: nurse-measured BP and BP measured by an automated device during 1 h resting in the clinic (basal BP). Hypertensive patients in an academic out-patients clinic were selected consecutively. We compared the relation of indices of early target organ damage (echocardiographically determined left ventricular mass index (LVMI) and urinary albumin excretion (expressed as albumin/creatinine ratio: ACR) to physician measured and nurse measured basal and ambulatory BP. The relation of BP to LVMI and the logACR were also studied for both sexes separately. Sixty-two patients (28 men, 34 women) were included, all untreated for >3 months. Systolic office BP was not significantly related to the LVMI (r2 = 0.04, P > 0.05), whereas nurse measured (r2 = 0.11, P < 0.05), basal (r2 = 0.13, P < 0.01) and ambulatory daytime (r2 = 0.13, P < 0.05) and night time (r2 = 0.17, p < 0.001) SBP did have a significant relation to LVMI. There was no difference in the relation of office, nurse, basal or ambulatory BP to logACR. In contrast to the highly significant relation of SBP to LVMI for male patients (day: r2 = 0.29, P < 0.01, night: r2 = 0.46, P < 0.001) this relation was non-existent for female patients (day: r2 = 0.09, P > 0.05, night: r2 = 0.02, P > 0.05). The relation between BP and logACR did not differ between the sexes. We conclude that: (1) to some degree nurse measured and basal BP may be considered as better predictors of early hypertensive target organ damage than physician measured BP; and (2) there is a pronounced sex difference in the relation of BP to left ventricular mass.