Objective: To evaluate the CH-Druck/Pressure Scan ERKA monitor for ambulatory blood pressure measurement according to the British Hypertension Society (BHS) protocol. Design: The BHS protocol consists of six phases: I, observer training and assessment; II, before-use interdevice variability assessment; Ill, in-use assessment; IV, after-use interdevice variability assessment; V, device validation; and VI, preparation of report. Method: Three CH-Druck/Pressure Scan ERKA recorders passed the before-use interdevice variability test, after which 89% of inflations recorded with these devices during the in-use phase gave valid readings, and the three devices subsequently passed the after-use interdevice variabilty test. The main validation test was carried out in 86 subjects with a wide range of pressures, the results being analysed according to the BHS grading system from A to D. Results: The CH-Druck/Pressure Scan ERKA acheived a grade A rating for both systolic and diastolic blood pressure, and satisfied the criteria for accuracy of the Association for the Advancement of Medical lnstrumentation (AAMI) with a mean difference (+ SD) for systolic pressure of - 3k 4 mmHg and - 21t 4 mmHg for diastolic pressure between the test device and the mercury sphygmomanometer. Subject acceptability was good and manufacturer's manual was satisfactory. Conclusion: On the basis of these results, the CH-DrucWPressure Scan ERKA can be recommended for ambulatory blood pressure measurement in clinical practice.