The use of metal-on-metal bearings in total hip arthroplasty is becoming increasingly popular. Several authors have reported excellent medium- and long-term results after the use of the Metasul metal-on-metal articulation (Sulzer Medica, Winterthur, Switzerland). We report a case of a loose Metasul liner eroding the neck of the femoral component resulting in extensive metallosis and weakening of the prosthesis.