Testing the accuracy of the automatic blood pressure measuring device Bosotron2®, we performed simultaneous, same–arm, comparative blood pressure measurements with three instruments (A, B, and C) of the device and by auscultation in the antecubital fossa by a trained observer in 24 volunteers each. The volunteers were evenly matched for age, sex, and blood pressure level. The mean systolic differences and their standard deviations (24 subjects each, n = 288 single measurements) were –1.32±3.8 mm Hg for instrument A, –0.99±3.9 mm Hg for instrument B, and –1.12±5.0 mm Hg for instrument C. The corresponding values for the diastolic differences were –2.71±4.4, –3.46±4.3, and –2.72±3.9 mm Hg, respectively. Combining the results for the three instruments, the comparison yielded a good accuracy (mean difference) and sufficient repeatability of the differences (standard deviation) for the systolic and diastolic blood pressures (systolic –1.14±4.3 mm Hg; diastolic –2.96±4.2 mm Hg). In addition to the British Hypertension Society protocol, in 33 patients with coronary artery disease the measurements using the three Bosotron 2 devices were compared with measurements within the aortic arch. The mean systolic/diastolic differences (±SD) were +1.45±4.3 and +7.27±4.7 mm Hg for instrument A, +4.70±12.8 and +1.73±7.4 mm Hg for instrument B, and –3.74±8.0 and +5.61±2.6 mm Hg for instrument C. Combining the results of the three instruments, the blood pressure was determined to be only slightly higher (systolic +1.74±9.6 mm Hg; diastolic +4.87±5.6 mm Hg) by the Bosotron 2® device as compared with the aortic arch pressure. The Bosotron 2® device seems to be suitable for clinical use and for monitoring blood pressure during clinical–pharmacological studies.