Abstract: In this study, a family of dynamic models of gear systems were incorporated with a wear formulation to predict the interactions between the dynamic behavior and tooth surface wear. First, dynamic response of a spur gear pair was predicted by using a finite elements-based deformable-body model and a simplified discrete model. These validated dynamic models were then combined with a surface wear model to study the interaction between gear surface wear and gear dynamic response. The predictions of the dynamic gear wear model demonstrated a considerable influence of worn surface profiles on dynamic tooth forces as well as a significant influence of dynamic tooth forces on wear profiles. A set of actual spur gear wear experiments was performed to generate experimental wear profiles that were shown to agree well with the predictions of the spur gear dynamic wear model. Next, the same dynamic wear methodology was applied to helical gears, by replacing the torsional nonlinear spur gear wear model with a three-dimensional linear model. Surface wear was shown to influence the dynamic response of a helical gear pair substantially, including the natural frequencies and forced response harmonic amplitudes. Consequences of dynamic behavior on wear outcome from a helical gear pair were less prominent when compared to spur gears. Finally, suitability of these gear pair dynamic wear models to a multi-mesh gear system was established by considering a single stage n-planet planetary gear set. The predictions indicated that the wear depths at the both internal and external meshes are significant and hence must be included in the simulations simultaneously. As in single gear pairs, surface wear was shown to impact the harmonic amplitudes of the dynamic response parameters, at the same time influencing the nonlinear behavior as well. Dynamic loads were also shown to affect the wear profiles at all meshes of a planetary gear set significantly. Higher wear amplitudes were predicted in the resonance region due to the increased dynamic mesh loads.