Purpose: This study evaluated overdentures retained by mini-dental implants (MDIs) as a treatment option for complete edentulism during a 3-year follow-up period. Materials and Methods: This observational clinical study included completely edentulous patients who were treated with MDI-retained overdentures. The MDIs were supplied by the manufacturer. Results: Twenty-three patients received 7 maxillary and 16 mandibular MDI overdentures retained by 110 MDIs. Of the 36 MDIs placed in the maxilla, 8 failed (in two patients), 2 had compromised survival, 3 displayed satisfactory survival, and 23 were successful. Of the 74 MDIs placed in the mandible, 11 displayed satisfactory survival and 63 were successful. The marginal bone loss was more pronounced for the MDIs placed mesially (intercalated), in areas of decreased ridge width and bone density, and with lower values of insertion torque. The overdentures fractured in seven patients; in 4 of them, this corresponded to the implant housing area. Self-reported reasons for patient dissatisfaction included occasional pain under the overdenture (n = 5) and instability of the maxillary antagonist complete denture (n = 4). Conclusion: Based on this research, considering its limitations, it is possible to conclude that survival rates and health status are better for MDI overdentures applied in the mandible than for those applied in the maxilla. The most severe prosthetic complications encountered were overdenture base fracture, matrix detachment, and instability of the maxillary antagonist denture. Keywords: denture, edentulous, mini-dental implants, overdenture