BACKGROUND The objective of this report is to combine the data from an earlier adult study with the data from a paediatric study in order to determine the overall accuracy of the BpTRU (BPM-100 model) as compared to the recognized standard, auscultatory mercury sphygmomanometer. METHODS The individual blood pressure points recorded for both adult and paediatric studies were compared directly to its corresponding observer reference measurements from data collected and stored from the two separate studies. There were 255 sets of readings in the adult study and 162 sets from the paediatric study, which were combined to make 417 pairs of blood pressure readings for this study. METHODS The overall observer standard reference mean for the 417 measurements was calculated and the difference between this and the overall mean BPM-100 was calculated with SD and ranges. Measurements within 5, 10 and 15 mmHg agreement were expressed as percentages. RESULTS A total of 121 subjects were included for this study (85 from the adult study and 36 from the paediatric study). From these, 417 paired measurements were recorded. The mean difference between the BpTRU and the reference standard systolic blood pressure (BP) was 0.47+/-5.40 mmHg with 89.2% measurements within 5 mmHg, 96.4% within 10 mmHg and 99.3% within 15 mmHg. The mean difference between the BpTRU and reference diastolic BP was -2.12+/-5.93 mmHg with 81.1% within 5 mmHg, 92.1% within 10 mmHg and 97.6% within 15 mmHg. CONCLUSIONS The BpTRU has been shown to be an accurate non-invasive blood pressure monitoring device in the general population over a wide range of ages (3-83 years). This combined study meets all requirements of the Association of Advancement of Medical Instrumentation and achieved a grade 'A' in the BHS protocol.