The subperiosteal implant was originally described in the 1940s. The inadequate long-term results of subperiosteal implants are in contrast to the excellent results documented for endosseous osseointegrated oral implants. Consequently, subperiosteal implants and other soft-tissue-anchored implants should not be used presently. Furthermore, these implants are seldom seen today, because they generally were removed rather shortly after placement. The present report documents a full 41-year history of a mandibular subperiosteal implant inserted in 1957 by focusing upon the consequences of not removing an implant in spite of continuous periods of complications during 4 decades. Implant exposure, inflammation, infection, and fistula formation occurred persistently. Total implant removal was refused by the patient in 1973. After 25 years without control, tremendous resorption of the mandible was observed in 1998. Consequently, the entire implant was then removed. Placement of osseointegrated oral implants was impossible without extensive autogenous bone grafting. The present report has demonstrated that regular control of patients with subperiosteal implants is mandatory. Furthermore, subperiosteal implants should definitely be removed, if continuous periods of complications occur.