The purpose of this study was to compare the corrosion behaviour under sliding wear of four materials commonly used for surgical implants: Ti-6Al-7Nb, Co-28Cr-6Mo, and two stainless steels, high-nitrogen stainless steel (Fe22Cr10NiN) and AISI 316L. A machine was constructed to simulate sliding wear, and the current density was measured to compare the response of each material to wear and to study the effect of pH (varied from 1 to 6). The results indicate that titanium exhibits higher current densities during wear than other materials tested over the pH range of 2.5 to 6. Additionally, pH has a greater effect on the corrosion behaviour of the two stainless steels than on the titanium or cobalt alloys.