The lifespan of titanium engineering parts can be significantly minced by wear damage. Protective coatings may improve wear resistance,however.coatings are known to adversely affect the fatigue behavior of titanium alloys leading to a fatigue debit to l>e considered by the designer. The relevant damage mechanisms have not yet been fully explored. The present study will shed light on the coating-substrate interplay. Two different coating deposition techniques and their effect on the fatigue behavior of titanium Ti-6A1-4V were investigated and compared TiN coatings were produced by physical vapor deposition and gas nitriding. The mechanical properties of the coated titanium alloy were determined by static tensile and fatigue tests; wear behavior was characterized using ball-on-disk tests. PVD coatings led to reduced fatigue strength whereas the gas nitride coating showed no effect. Post-failure analysis revealed that the coating microstructure strongly influenced the failure mode. Moreover, the coating thickness,hardness,roughness and the residual stresses in the coating played an important role. According to the experimental results, the fatigue resistance of the bulk titanium alloy was mainly affected by residual stresses in the coating and across the coating-substrate interface. Coating microstructure variations resulted in property changes of the coating which in turn altered the fatigue response of each coating-substrate system.