Abstract: A method and apparatus for determining mean blood pressure involves the use of a pre-programmed microprocessor which interprets pressure oscillation values from a pressure cuff affixed to a subject's limb. The pressure cuff is inflated to a value above apparent systolic pressure and then deflated in steps. The steps are all substantially equal mmHg declinations in cuff pressure. At each step cuff oscillation values are taken and stored. The greatest cuff oscillation and its associated cuff pressure are noted, along with the next greatest cuff oscillations and associated cuff pressures on either side of the greatest oscillation. The actual means blood pressure is then determined by forming a window adjacent to the greatest oscillation and calculating, on which side of the greatest oscillation, within the window, the means pressure is disposed.