Examination of retrieved orthopedic implants has identified fretting corrosion as one of the principal mechanisms of implant corrosion. Fretting may contribute to corrosion and metal ion and particle release directly, or may contribute to the initiation of crevice corrosion. A series of experiments have been conducted, as per F897. When fretting against itself, Ti 6Al 4V tends to gall and show high fretting corrosion rates. In mixed metal combinations with stainless steel or cobalt alloy, fretting corrosion of titanium is significantly reduced. Similarly, nitriding one or both faces reduces corrosion. The addition of serum proteins to a saline solution tends to increase the fretting corrosion rates. Fretting in cell culture growth media is higher in those media containing higher calcium ion concentrations or containing hydrogen peroxide.