A more precise value of the half-life of U235, for alpha emission, has been determined from an analysis of the alpha spectrum of natural uranium. The alpha spectrum was measured using solid-state detectors and the half-life obtained by a comparison of the intensity of the resolved portion of the U235 alpha spectrum with the intensities of the U234 and U238 alpha groups. The value obtained was T1/2 = (6.92± 0.09) × 108 years.