Ultrasonically assisted turning is one of the modern machining processes developed in recent decades to facilitate machining of hard-to-cut materials which are widely used in different industries. Cutting tool wear is one of the main problems in machining of hard materials which has necessitated implementation of modern machining processes such as ultrasonically assisted turning. Due to vibro-impact conditions, cutting tool failure takes place when ultrasonically assisted turning is applied for hard and brittle materials. In fact, microchipping takes place in the tool nose after machining of short length, so sharp cutting edge fails at the early stages of cutting. Therefore, if the sharpness of cutting edge is removed before the machining, the fracture of cutting edge, caused by vibro-impact condition, will be eliminated. The aim of this research is to investigate the tungsten carbide tool flank wear in ultrasonically assisted turning of hardened alloy steel in comparison to the conventional turning. Therefore, a proper experimental ultrasonic vibration configuration was designed to apply the ultrasonic vibrations to the turning tool along cutting direction. Experiments were carried out for different cutting speeds below the critical speed in ultrasonically assisted turning. Application of the tool with modified specifications led to make an initial wear on tool flank, but finally a significant improvement of tool wear was observed.