Purpose: The purpose was to compare the clinical, radiographic, and prosthetic results of an All-On-Four maxillary hybrid prosthesis and a bar-clip retained maxillary overdenture after one year of follow-up in patients with mandibular hybrid prostheses. Materials and methods: Twelve participants with completely edentulous maxillae and mandibular hybrid prostheses were selected. Participants were randomly assigned to one of two groups: All-On-Four maxillary hybrid prosthesis group (HP) and bar-clip retained maxillary overdenture (BO) group. In the HP group, the patients received four implants in accordance with the All-On-Four concept. The implants were functionally loaded with maxillary fixed detachable hybrid prostheses. In the BO group, the patients received four parallel implants supporting bar-clip retained overdentures. Results: At 12 months, there were significant differences in gingival and plaque indices and probing depth between both groups for anteriorly placed implants. For anterior implants, there was no difference in implant stability or marginal bone loss between the two prostheses. Group comparisons at the posteriorly placed implants revealed significant differences in plaque and gingival indices at 12 months. The total number of prosthetic complications required for the BO group was significantly higher than for the HP group. Conclusion: Within the limitations of this study, it was possible to conclude that, in patients with mandibular hybrid prostheses, both All-On-Four hybrid prostheses and bar-clip retained overdentures may be effectively utilized for rehabilitation of the edentulous maxilla using four implants since the clinical, radiological, and prosthetic outcomes were clinically acceptable and manageable.