Peripheral arterial disease (PAD) remains underdiagnosed by primary care and cardiovascular physicians. The office-based assessment of PAD is limited by the need for specialized equipment and the time required for performance of the ankle-brachial index (ABI). We explored whether the accuracy of automated ABI measurement by oscillometry compared favorably with the gold-standard method using continuous-wave Doppler ultrasound. Consecutive patients referred to our university hospital noninvasive vascular laboratory for ABI measurement were invited for participation. Of 205 patients, 201 participated, including 55 with PAD. The ABI was measured by automated oscillometry and Doppler ultrasound. The test of trends revealed a correlation coefficient of 0.78 in the left leg and 0.78 in the right leg (P<0.01 for both). The mean ABI difference between methods was 0.04+/-0.01 and 0.06+/-0.01, respectively, in the left and right legs. The differences between the methods followed a normal distribution. Oscillometric determination of the ABI provides an accurate determination of the ABI in an outpatient population. Our findings show automated oscillometry to be a reliable and easier method of ABI measurement, lowering the barrier to incorporation of this diagnostic test into clinical practice.