Objective: To perform a clinical validation for a semi-automatic arm-type device DA-704 (A&D Company, Ltd., Tokyo, Japan) according to the British Hypertension Society protocol. Methods: Eighty-five study participants (37 men) were included. The mean age was 50.1 ± 17.0 years, systolic blood pressure range was 79-212 mmHg and diastolic blood pressure range was 43-118 mmHg. For each participant, three readings of the UA-704 were compared with simultaneous auscultatory measurements by two trained independent observers. The observers used a mercury calibrated sphygmomanometer and a dual stethoscope. The results were graded according to the 1993 British Hypertension Society protocol. Results: The average difference between mercury sphygmomanometer and UA-704 readings was -1.85 ± 4.26 mmHg (mean ± SD) for systolic blood pressure and -1.44 ± 3.97 mmHg for diastolic blood pressure. The proportions of values agreeing to within 5, 10 and 15 mmHg were 79.2%, 96.5% and 99.6% for systolic blood pressure and 86.7%, 96.9% and 99.6% for diastolic blood pressure for the observers and device (A/A grade for British Hypertension Society). Conclusions: For an adult population, the UA-704 device for self-measurement of blood pressure achieved a British Hypertension Society grade A/A and therefore can be recommended for home blood pressure monitoring. © 2005 Lippincott Williams & Wilkins.