The accuracy of automated office blood pressure (BP) devices in severely obese individuals is unknown. In an exploratory study, we compared standardized BP measurements using a BpTRU device with those taken using a WatchBP Office monitor. Paired t-tests, Bland–Altman plots, and Pearson’s correlations were used to compare devices. A total of 62 patients were analyzed: their mean age was 39.5±9.3 years and their mean BMI was 45.1±5.7 kg/m2. Fifty-five patients (89%) were women and 21 (34%) had a diagnosis of hypertension. The mean BpTRU values were 117.2±12.7/76.7±9.7 mmHg and the mean WatchBP measurements were 126.6±13.8/79.7±10.9 mmHg [difference of −9.4±11.6 for systolic (P<0.0001) and −3.0±7.7 mmHg for diastolic (P=0.003)]. A Bland–Altman plot for systolic BP showed considerable variability. Only four (6.5%) patients had hypertension (>140/90 mmHg) according to BpTRU versus 15 (24%) according to WatchBP. In conclusion, the mean BP measurements taken using two commonly used automated office devices differed markedly and by a clinically important magnitude. These data indicate the need for formal validation of these devices specifically in severely obese individuals.