In the current study, the influence of elastic deformation in thin film hydrodynamic lubrication was numerically investigated. The one dimensional Reynolds equation was solved with considering the piezoviscosity effect of the lubricant and elastic deformation of the sliding surface in flat-flat contacts. The contact area comprised of a stationary rigid surface with sine waves with amplitude of several nano meters and a moving flat compliant surface. The obtained numerical results show that small amplitude of roughness compared with the averaged film thickness influences the pressure distribution of the hydrodynamic film. Reduction of the roughness and decay in wave of the roughness occurred because of the elastic deformation induced by local pressure generation.