The ultrasonic cw resonance technique was used to measure the adiabatic elastic constants of single‐crystal aluminum antimonide at 27°C. The values for the elastic stiffness constants, in units of 1011d/cm2, are:c11= 8.939,c12= 4.427, andc44= 4.155. A theoretical density of 4.36 g/cc was used. The values ofc11andc44for single crystal GaSb obtained by the cw resonance technique are compared with previous values obtained by pulse‐echo techniques.