An oscillometric, noninvasive blood pressure monitor comprising an inflatable cuff adapted for placement around a body member, a pump for cuff inflation, a pressure transducer connected to the cuff, means for detecting oscillations in arterial pressure occurring during a transition in cuff pressure between a pressure greater than normal systolic pressure and a pressure less than normal diastolic pressure, and a blood pressure measurement circuit which is capable of determining the maximum amplitude (A_m) of the oscillations, identifying mean cuff pressure (P_m) as the coincident value of the cuff-pressure signal from the pressure transducer, and determining systolic pressure as a function of both A_m and P_m. In accordance with one aspect of the invention, the blood pressure monitor has an optical sensor including a light source and photodetector optically coupled to the body member proximate to the cuff. Oscillations in the output signal of the photodetector are detected, and the blood pressure measurement circuit determines the oscillation amplitude corresponding to systolic pressure (A_s) as a function of both A_m and P_m.