Objective The effective lubrication performance of the metal-on-metal hip implants only requires the optimum conformity within the main loaded area, while it is advantageous to increase the clearance in the equatorial region. Such a varying clearance can be achieved by changing the radius of the curvature of the surfaces of the components. Alpharabola is one specific example of such surfaces. The aim of this study was to investigate the EHL performance of a novel prosthesis employing Alpharabola cup under realistic walking conditions. Method A transient elastohydrodynamic lubrication model was created for this novel hip prosthesis. A normal walking gait was represented by the ISO specified dynamic operation conditions. Complete numerical solutions were obtained by solving the Reynolds equation in spherical coordinates, the film thickness equation and the load balance equations using Multi-grid technologies. Results Detailed variations in film profile and pressure distribution during one convergent walking cycle were analyzed. The effect of parameter ? on quasi-static and transient solutions of the central and minimum film thicknesses and maximum pressures was investigated. The transient and quasi-static solutions for the same parameter ? were compared. The lubrication performance of Alpharabola hip prostheses and that of a spherical hip prosthesis were compared under both transient and quasi-static conditions. Conclusion It was found that both the squeeze film action and the non-spherical acetabular surface can significantly improve lubrication performance under realistic walking conditions, in increasing the predicted lubricant film thickness and decreasing the maximum hydrodynamic pressure. The metal-on-metal Alpharabola hip prosthesis was shown to benefit from fluid film lubrication significantly more than spherical hip prostheses.