A device for non-invasive measurement of blood pressure includes a blood pressure cuff, a plethysmographic electrode for acquiring an impedance plethysmogram distal to the cuff and a processing device to inflate and deflate the cuff, generate the impedance plethysmogram and to determine the systolic and diastolic blood pressures. It is determined when the cuff is completely occluding the extremity, e.g., by detecting pulses at a second, partially occluded cuff or by a photoplethysmogram attached to the big toe. The device can be used to measure systolic or diastolic blood pressure or both. It can also be used to take ankle-brachial measurements. An autocorrelation technique can be used to correct noise.