The adiabatic elastic moduli at 25°C for single crystal alpha‐uranium are reported here as derived from measurements of high‐frequency ultrasonic wave velocities. A detailed description is given of the specimens used, and of the technique employed for obtaining small plates of proper orientation suitable for the problem. Although the specimens were small the technique of measurement produced results of relatively good precision, as evidenced by the numerous cross checks obtained. Best values of the moduli and the estimated probable errors are given.The elastic stiffness moduli in units of 1012dynes/cm2are as follows:c11=2.147 ±0.14%,c12=0.465±0.6%,c13=0.218±1.5%,c22=1.986±0.14%,c23=1.076±0.34%,c33=2.671±0.14%,c44=1.2444±0.10%,c55=0.7342±0.10%,c66=0.7433±0.10%.