Accurate determination of the transaortic valve gradient has required two catheters, one in the left ventricle and one in the ascending aorta. We now report a new technique for measurement of the transaortic valve gradient from the simultaneous left ventricular (LV) and femoral artery (FA) pressure tracings. This technique was compared with the "true" gradient obtained by measurement of the simultaneous LV and central aortic pressures, and is accurate (R = 0.999) and relatively simple. Other approaches used to determine the mean transaortic valve gradient were less accurate: simultaneous LV-FA (R = 0.991); aligned LV-FA (R = 0.974); averaged simultaneous and aligned LV-FA (R = 0.981); and nonsimultaneous LV-aorta pullback (R = 0.953). Thus, this new technique provides an accurate transaortic valve gradient without requiring the use of two central catheters.