The main purpose of this study is to analyze the contact stresses at the interface between the piston-balls and the swash plate of the axial hydrostatic motor, for two constructive solutions. Contact problems are highly nonlinear and required significant resources to solve. In this study, three-dimensional elastic-plastic stress analysis of sliding contact is conducted on 3D piston-swash plate model. The contact pressure distributions are calculated using elastic Hertz theory and finite element method for two constructive solutions. For every solution it was analyzed the influence of the geometric dimensions of the parts in contact.