In certain applications, it is improtant to measure the mechanical properties of steel with high accuracy. These properties are usually measured by destructive methods. However, the small changes made during heat treatment processes are not usually detectable by destructive methods. Ultrasonic non destructive testing is an alternative method that can be used for measuring the mechanical properties of steels. In this paper, the ultrasonic method has been used for measurement of meachanical properties of AISI D6 steel samples processed by various heat treatment processes. Each sample has a differnet micro stucture and hardness due to its specific heat treatment. To find the meachanical properties, the velocity of longitudinal and shear ultrasonic waves were measured for each sample. Comparison of the results obtained from ultrasonic measurements with those available in reference tables shows that the ultrasonic non destructive method can measure the elastic properties of AISI D6 samples with high accuracy.