Abstract: Circular model, assuming limiting shear stress as an intrinsic property of the lubricant, was incorporated into Reynolds equation to simulate slip effect from elastohydrodynamic lubrication (EHL) to hydrodynamic lubrication (HL) regimes. With increasing speed, coefficient of friction showed an abnormal wave, together with an inlet dimple appears on the contact profile. Effects of load, speed, reduced modulus of elasticity and slide-roll ratio were examined. Boundary slip was verified to produce abnormal contact profile and friction variation.