A blood pressure measurement system that non-invasively determines an individual's blood pressure can include a noninvasive blood pressure sensor having an optical sensor and a motion sensor. The optical sensor can provide a photoplethysmograph signal obtained from a patient to a processor. The motion sensor can provide a motion signal to the processor responsive to motion of the patient. In one embodiment, the processor calculates or estimates the blood pressure of the patient based on the photoplethysmograph signal and the motion signal. Advantageously, the system can obtain this blood pressure measurement without an occlusive cuff, thereby reducing patient discomfort. In other implementations, the processor calculates a blood pressure-related parameter from the photoplethysmograph and motion signal. The processor can occasionally trigger an occlusive cuff measurement as this parameter changes, thereby reducing the frequency of occlusive cuff measurements.