Although there are AAMI and BHS standards for accuracy of electronic home electronic blood pressure monitors (HBPM), patient composition differences and differences in manufacturer's algorithm for calculation of the systolic and diastolic measurement may result in measurement differences between monitors. The aim of this study was the measurement of differences among HBPM. Paired comparisons were performed between the Omron 712c electronic home monitor and each of 12 other HBPM (Sunbeam 7654, Sunbeam 7623, Omron 711, Omron 432c, A&D-UA767, Lumiscope 1085M, Omron 725CIC, Assure A30, Lumiscope 1083N, Omron 815, Omron 605, and Assure BD-W20), in addition to comparison to the auscultatory method by trained observers. Measurements were made in normotensive subjects in an ambulatory setting. The main outcome measures were systolic and diastolic blood pressure measurements. All of the HBPM, except for the Sunbeam 7654 and the Assure A30/ BD-W20 (wrist) models, demonstrated small differences of <4/4 mm Hg for systolic/diastolic measurements with pulse measurement differences of <3 beats/min. These differences were less than the differences previously reported for office BP auscultation of 6/5-10 mm Hg for systolic/diastolic measurements. The Omron 712c, passing previous AAMI and BHS standards, measured the systolic reading within 2 mm Hg of auscultatory mercury or aneroid measurement and under-measured the diastolic by 6-9 mm Hg. Differences in the patient composition studied could account for the difference. The wrist and finger manometers performed clinically similar to the Omron 712c, except for the Assure BD-W20, which overmeasured the diastolic by 7 mm Hg. It is concluded that the small differences among the various HBPM, which are less than those in clinical office auscultation, should encourage greater use of electronic manometers in the office and at home.