The deposition of titanium on a titanium alloy substrate is being examined for potential use as a surface treatment for medical prostheses. A titanium alloy, Ti6Al4V, was coated with pure titanium using the cold gas dynamic spray, CGDS, deposition method. CGDS involves the impact of particles at high velocities (typically greater than 600 m s^-1) and allows the application of coatings at low temperatures. In the current work, coatings were deposited onto samples with two different surface preparation methods (as-received and grit blasted). Prior to spraying, surface textures were characterised by profilometric techniques. The fatigue life of the as-received and grit blasted materials, both before coatings and following coating, was measured in a rotating-bend fatigue system. A reduction in fatigue life was observed following the application of a cold spray titanium coating. Scanning electron microscopy (SEM) has been employed to understand the role of the coating in the fatigue behaviour. The reduction in fatigue life has been related to the microstructure of the coatings and to the processes operating during deposition.