This paper presents the effects of circumferential groove on the minimum oil film thickness in engine bearings. The fluid film pressures are calculated by using the infinitely short bearing theory for the convenience of analysis. Journal locus analysis is performed by using the mobility method. A comparison of minimum oil film thickness of grooved and ungrooved bearing is presented. It is found that circumferential $360^{circ}$ groove only reduces the absolute magnitude of the oil film thickness, but $180^{circ}$ half groove affects the shape of film thickness curve and position of minimum oil film thickness.