In conventional grinding of hard to cut materials such as Ti6Al4V alloys, surface burning, redeposition and adhesion of chips to the grinding wheel and workpeice occur visibly unless it is carried out at low speeds and with high volume of cutting fluid. Ultrasonic assisted grinding is an efficient machining process which improves the machinability of hard-to-cut materials by changing the kinematics of the process. In this research, the effect of imposition of ultrasonic vibration on the grinding of Ti6Al4V alloy is studied. Longitudinal vibration at ultrasonic frequency range (20kHz) is applied on the workpiece and machining forces and surface roughness are compared between conventional grinding (CG) and ultrasonic assisted grinding (UAG) processes. An ultrasonic setup is designed, optimized and fabricated based on combination of mathematical modeling, FEM analysis and genetic algorithm. Comparison between CG and UAG at several cutting and feed speeds and cutting depths are carried out, and the effect of ultrasonic vibration in dry condition is also studied. The results show reduction of grinding forces and improvement of surface roughness when ultrasonic vibration is applied on the workpiece