Background: Recent studies suggest that a reduced delay during automated office blood pressure (AOBP) measurement may be as accurate as a 5-minute delay. The clinical impact of this change compared to gold-standard assessments (i.e. 24-hour ambulatory BP monitoring, ABPM) has not been reported. Objective: To compare the impact of a 3- vs 5-minute delay on AOBP and its relation with average awake-time ABPM. Methods: Patients referred to a single hypertension (HTN) center had BP measurements with ABPM and one of two non-randomized, unattended AOBP protocols. Half of patients underwent AOBP with a 5-minute delay; the other half underwent AOBP with a 3-minute delay. All measurements were compared to the average awake-time ABPM. HTN was defined as SBP≥140 or DBP≥90 mmHg. We used linear regression adjusted for age, sex, and race to assess whether the 3-minute protocol was associated with a difference between mean AOBP and average awake-time ABPM. Results: Among 100 participants (mean age 59.7±15.5 years, 58% women, 26% Black), the average awake-time BP was 132.6±14.8/77.4±11 for the 5-minute protocol and 134.4±17/78.2±11 for the 3-minute protocol. HTN misclassification between groups based on awake-ABPM was similar (14% for 5- versus 12% for 3-minute delay, p=0.51). Compared to 5-minute delay, 3-minute delay was not associated with a significant difference between mean AOBP and mean awake-time ABPM for SBP (2.3 mm Hg; 95% CI: -3.7, 8.2) or DBP (1.2 mm Hg; 95% CI: -2.5, 4.8). Conclusion: Measuring AOBP with a 3-minute delay did not result in statistically different accuracy compared with average awake-time ABPM. However, this finding should be confirmed in a larger, clinic-based sample.