OBJECTIVES: To perform simultaneous invasive comparative measurements in order to validate the blood pressure self-measuring device OMRON R3 for use on the wrist, in accordance with protocol 58130 of the German Institute for Validation. METHODS: Five consecutive comparative blood pressure measurements were carried out for each of 15 patients (n = 75 measurements). The blood pressure was measured simultaneously non-invasively using the blood pressure self-measuring device OMRON R3 around the left wrist and at the same time invasively using a pigtail catheter situated in the aortic arch. The pressure curves were drawn continuously. The measuring arrangements, validation of the invasive-measurement unit and evaluation were all carried out in accordance with protocol 58130. RESULTS: The blood pressure self-measuring device OMRON R3 for use on the wrist satisfied the criteria of the European Standard prEn 1060-3. The OMRON systolic values were 2.2 +/- 3.9 mmHg higher and the diastolic values were 0.2 +/- 2.7 mmHg lower than the invasive ones. However, for higher blood pressure levels (> 150 mmHg), the device tested displayed an increasing tendency to underestimate the systolic blood pressure in one-third of the patients by 5-15 mmHg, compared with the invasive measurements. No faulty measurements occurred with the patient group examined. CONCLUSION: The blood pressure self-measuring device OMRON R3 for use on the wrist can be recommended for blood pressure self-measurement. When it is used correctly, it measures the blood pressure reliably and accurately.