One directional and elliptical vibration cutting of IN738 at ultrasonic frequency has been investigated both experimentally and by FEM in the present study. The influence of each process on the cutting force was studied. The FEM modeling was carried out by using MSC-MARC. The results were compared with the experimental findings of the conventional cutting. The ultrasonic vibration was applied to a rigid cutting tool along the cutting velocity in one directional vibration cutting. In elliptical vibration cutting the vibration was applied both along the cutting velocity and in the chip flow direction. The experiments were carried out on an ultra precision CNC lathe with single crystal diamond tools. The same effects were confirmed in the machining practice and by FEM. It was quite feasible when machining IN738 to obtain the advantages of elliptical vibration cutting already reported for some other materials such as copper, aluminum, tungsten and super alloys.