Ion implantation is shown to retard surface slip and thereby induce improvements in wear and fatigue resistance of metals. A simple test is described which can be used to study the effects of ion implantation in retarding motion of dislocations in the near-surface regions of metals. In this test, regions of annealed and etched surfaces of metals are masked and implanted with ions. The specimens are then deformed until significant plastic deformation is introduced and the slip-lines are observed under the microscope. Evidence of improved resistance to slip-line formation in nitrogen ion implanted surface regions is presented for copper, α-iron and 303 stainless steel. The test is shown to be a useful tool for comparing the effects of ion implantation conditions on surface slip retardation, since adjacent regions of the surface can be implanted to different conditions and the resistance to slip line formation in the different regions can be compared. For example, the resistance to slip line formation in 303 stainless steel was found to be greater in regions that were implanted at ultrahigh current densities (1500 μA/cm2) than in regions implanted at lower current densities (100 μA/cm2) to the same dose and at the same ion energy.