Development of additive manufacturing (AM) has opened up new opportunities for fabrication of metallic structural materials. Additive Friction Stir (AFS) is a new technology being developed at Aeroprobe Corporation, which can be used for additive manufacturing, coating, and joining. Because it is a solid-state process, AFS eliminates problems such as porosity, hot cracking, segregation and dilution which are commonly associated with fusion-based techniques to create high quality parts. Using AFS, many metallic materials including Al alloys, Mg alloys, Cu alloys, Ni-based superalloys and steels have been successfully deposited at Aeroprobe. In this presentation, AFS deposition of Ti-6Al-4V, the most widely used titanium alloy, will be discussed. The microstructure and mechanical properties of AFS Ti-6Al-4V will be studied. It is expected that AFS processing can create small prior- grains with fine - lamellar structure in deposited Ti-6Al-4V alloy, leading to improved mechanical properties.