Purpose: This work compared implant-supported fixed prostheses and overdentures in the edentulous mandible in a randomized prospective study of treatment results, clinical working hours, laboratory working hours, and laboratory costs including materials. Materials and Methods: Seventeen subjects agreed to participate. Three standard Brånemark implants were placed between the mental foramina in each patient. After the connection of standard abutments, subjects were randomly assigned to the fixed prosthesis group (n = 11) or overdenture group (n = 6). Subjects in the fixed group were provided with prostheses according to the All-in-One concept. Subjects in the overdenture group received a conventional denture retained by a Dolder bar system. Results: One implant was lost in the fixed prosthesis group after 1 year. A new implant was placed, and the prosthesis was refitted. Mean clinical working hours were 3.1 in the fixed prosthesis group and 4.1 in the overdenture group. Mean laboratory working hours were 12.5 in the fixed prosthesis group and 7.7 in the overdenture group. Total laboratory costs, including materials, were on average about US$1,700 for the fixed prosthesis and US$1,350 for the overdenture. Conclusion: A fixed implant-supported prosthesis in the edentulous mandible could be provided at about the same cost as an overdenture using the method described. Provided that the early survival results prove to be long lasting, the choice between a fixed and a removable prosthesis need not be a matter of economy.