Subperiosteal implants used to be prescribed to partially and fully edentulous patients to restore occlusion and esthetics prior to the emergence of the more successful endosseous implants that are used today. Because subperiosteal implants had a high incidence of failure, difficulty of placement, and post-operative complications, the use of subperiosteal implants declined significantly. However, some subperiostal implants placed 20-30 years ago still survive. Little information is available in the literature on how to treat patients whose subperiosteal implants still remain. This clinical case report thereby describes a treatment for a patient with a maxillary subperiosteal implant placed 23 years ago. The patient was offered a treatment option that included surgical implant removal, bone grafting and placement of endosseous implants to support a new maxillary overdenture. This treatment plan was not feasible due to the financial constraints of the patient and the complexity of the treatment. The patient chose a more conservative treatment plan, preserving the existing implant. The existing maxillary subperiosteal implant was restored with MICRO ERA attachments and a maxillary implant-retained overdenture was fabricated. The patient was satisfied with the esthetics and functional aspects of the treatment. No further peri-implant bone loss or other complications were found after a six-month recall. This clinical report suggests an alternative treatment plan for patients with existing subperiosteal implants that wish to avoid complex surgical procedures.