Do elderly similarly to younger hypertensive patients tend to be overtreated if therapeutic decisions are based exclusively on blood pressure measured by the physician in his office? Eighteen hypertensive patients (10 previously treated) aged 70 years or more had repeatedly office systolic blood pressure greater than or equal to 170 mm Hg and/or diastolic blood pressure greater than or equal to 100 mm Hg. The physicians in charge were asked to reduce blood pressure within 4 months to a target of less than or equal to 160/95 mm Hg using any drug regimen. Blood pressure was monitored during daytime using a noninvasive blood pressure recorder, but the results of the recording were not available to the physicians until the end of the study. At the outset, 11 patients had a mean ambulatory recorded blood pressure less than 170/100 mm Hg. Those patients who exhibited high blood pressures only in the doctor's presence did not reduce their ambulatory blood pressure when antihypertensive therapy was initiated or intensified in order to reduce office blood pressure. This contrasted with the significant fall in ambulatory blood pressure observed in the presence of the doctor. Thus ambulatory blood pressure monitoring seems useful to avoid overtreatment not only of younger but also of elderly hypertensive patients.