Grain growth in Ti6Al4V alloy during fusion welding decreases yield stress and tensile strength. This study examined the effect of mechanical vibration of the work piece during GTAW welding on the mechanical and metallurgical properties of Ti6Al4V. The structures of all welded specimens at different levels of vibration was examined and it was found that, during 330 Hz vibration, grain size in the welded metal zone decreased significantly over that of pieces welded without vibration. GTAW at 330 Hz significantly increased the mechanical properties and produced the highest yield strength, tensile strength and percentage of elon gation. The highest level of hardness in the welded metal zone was achieved under this condition.