The value of combined multisegmental pressures and quantitative Doppler flow velocity determinations in the preoperative vascular laboratory evaluation was analyzed in 100 consecutive patients with angiographically documented peripheral arterial occlusive disease. Several new observations were made: (1) erroneously normal or even high segmental pressure readings appear to be caused by increased arterial wall stiffness and may produce falsely elevated or erroneously normal pressure, suggesting less disease than exists, especially when only ankle pressure screening is used. (2) The addition of quantitative flow velocity determinations significantly improved the reliability of diagnostic decision making. The diagnosis of proximal arterial occlusive disease based on combined pressure-velocity measurements was confirmed angiographically in 143 of 148 limb studies (96.6%), including several with normal pressures and reduced velocity values--a pressure-velocity dissociation. (3) A decrease of the leg segment:arm pressure ratio combined with only a slight reduction of velocity indices suggests a stenosis with good local collateral flow and vessel patency at the site of measurement--a reversed pressure-velocity dissociation. (4) A decreased lower limb segment/arm pressure ratio combined with a significant reduction of velocity indices is evidence of arterial stenosis with poor local collateral flow. The combined multisegmental pressure and velocity evaluation of patients suspected of arterial occlusive disease substantially increases the reliability of noninvasive diagnosis and offers a new level of differential diagnostic interpretation.