OBJECTIVE: To validate the SpaceLabs 90207 ambulatory blood pressure monitor in the elderly. METHODS: Eighty-five subjects aged 60-90 years were recruited from hospital inpatients. Using the same-arm sequential measurement technique two observers recorded blood pressure with a mercury sphygmomanometer first and then by using the SpaceLabs 90207 ambulatory monitor. This set of blood pressure readings was performed three times with all 85 subjects supine, sitting and standing. Data were analysed according to the British Hypertension Society protocol. RESULTS: Over the blood pressure range tested the SpaceLabs 90207 device recorded diastolic blood pressure (DBP) satisfactorily, achieving grade A in all body postures, but not systolic blood pressure (SBP; supine D, standing C, sitting C). However, at SBP </= 160 mmHg, satisfactory performance was achieved in sitting (B) and standing (B) patients, but not in supine patients (C). With higher blood pressure there was increasing underestimation by the SpaceLabs 90207 device of SBP and DBP compared with those recorded by the mercury sphygmomanometer (supine SBP r = -0.42, P < 0.001; DBP r = -0.21, P = 0.05; sitting SBP r = -0.43, P < 0.001; DBP r = -0.5, P < 0.001; standing SBP r = -0.34, P = 0.002; DBP r = -0.24, P = 0.003). CONCLUSION: The SpaceLabs 90207 blood pressure monitor appears satisfactory for clinical use in elderly subjects over a wide range of DBP levels, but with increasing SBP its performance diminishes, particularly in the very high SBP range.