OBJECTIVE: To perform clinical validation of the TM-2564G device (A&D Company, Ltd, Tokyo, Japan) for in-hospital blood pressure measurement according to the British Hypertension Society protocol. METHODS: The tests were carried out on 85 patients aged 19-82 years (41 male patients, mean age 50±19 years) with systolic blood pressure 75-219 mmHg and diastolic blood pressure 43-117 mmHg (mean 142±33/85±20 mmHg). For each patient, three readings of the TM-2564G device were compared with simultaneous auscultatory measurements by two trained independent observers. The observers used a mercury-calibrated sphygmomanometer and dual stethoscope. The results were graded according to the British Hypertension Society protocol 1993. RESULTS: The average difference was -1.85 mmHg for systolic blood pressure and -1.20 mmHg for diastolic blood pressure. The standard deviation of the difference between TM-2564G and the observers' results was 4.85 and 4.16 mmHg for systolic and diastolic blood pressures, respectively. Systolic blood pressure percentage of readings agreeing to within 5 mmHg was 75.7%, 10 mmHg 95.36% and 15 mmHg 99.6%, and for DBP 82.7, 97.6 and 99.8%, respectively. CONCLUSIONS: The TM-2564G device achieved A/A British Hypertension Society grade and can be recommended for in-hospital measurement of blood pressure. © 2005 Lippincott Williams & Wilkins, Inc.