We revised an acrylic femoral hip prosthesis to a total hip prosthesis for an 86-year-old female. The implant was made of dental resin and had functioned for 56 years in situ, though its stem had broken. Because of no osteolytic reaction, the reconstruction was relatively easy. From the result of histologic and radiologic examination, the bio-inertness of material and uncemented fixation seemed to contribute the minimum bone loss and to the favorite spontaneous arthrodesis after providing good joint function in her middle age.