This paper describes a study on the load bearing capacity of newly developed high density sintered metal gears with surface-densification. High density sintered metal gears were hobbed, and then surface-rolled. These gears were case-carburized after surface-rolling. The effect of surface-rolling on the surface property was examined by measuring porosity and hardness near surfaces of rolled gears. Running tests for these gears were performed. A failure mode and load bearing capacity of high density sintered metal gears and the effects of surface-rolling on the load bearing capacity of sintered metal gears were determined, and the results were compared with those of carburized wrought steel gears and conventional sintered metal gears. The experimental results show that the load bearing capacity of a newly developed high density sintered metal gear with surface-densification is higher than that of a carburized wrought steel gear. This paper describes a study on the load bearing capacity of newly developed high density sintered metal gears with surface-densification. High density sintered metal gears were hobbed, and then surface-rolled. of surface-rolling on the surface was was examined by measuring porosity and hardness near surfaces of rolled gears. Running tests for these gears were performed. A failure mode and load bearing capacity of high-density sintered metal gears and the effects of surface-rolling on the load bearing capacity of sintered metal gears were determined, and the results were compared with those of carburized wrought steel gears and conventional sintered metal gears. The experimental results show that the load bearing capacity of a newly developed high density sintered metal gear with surface- densification is higher than that of a carburized wrought steel gear.