Previous recommendations for use of pneumatic tourniquets in extremity surgery suggest parameters for maximum pressure and time limits without regard for optimum cuff width. Wide cuffs produce lower readings of blood pressure relative to narrow cuffs, presumably because the wide cuffs arrest flow at lower inflation pressure. We investigated three tourniquet sizes and the inflation pressure required to eliminate flow to the upper extremity using an ultrasonic Doppler device to monitor blood flow in the radial artery of ten normal subjects (arm circumference 24.5 to 37 cm). Arterial flow was always eliminated at the lowest pressure using the widest tourniquet cuff. Significantly lower inflation pressures will eliminate blood flow if wider tourniquet cuffs are used; therefore, use of a wider tourniquet cuff may result in a reduced incidence of tourniquet complications.