Purpose: This study was conducted to evaluate the effect of using posterior support by bilateral short implants on bone height changes around two anterior mini implants used for retaining mandibular complete overdenture. Materials and Methods: Six completely edentulous patients of age ranged between 55 and 65 years were selected for this study. Patients were randomly classified into two equal groups. Group (A)patients that would be delivered mandibular complete overdenture retained by two canine mini dental implants with ball attachments without posterior support by short implants.Group (B) patients that would be delivered mandibular complete overdenture retained by two canine mini dental implants with ball attachments with posterior support by bilateral short implants with healing abutments (in first molar regions). The alveolar bone height changes around mini-implants were radiographically evaluated at the time intervals: T0 (immediately), T6 (6 months), T12 (12 months) and T18 (18 months) after mandibular overdenture insertion using standardized periapical radiographs. Results: In this study, when comparing between the means of peri-implant VBL during the 1st and 2nd 6 months in each group, a statistically insignificant decrease in peri-implant VBL was found during the 2nd 6 months. When comparing between peri-implant VBL during the 2nd and 3rd 6 months of the study, a statistically significant decrease in peri-implant VBL was found during the 3rd 6 months in group B while a statistically insignificant decrease in peri-implant VBL was found during the 3rd 6 months in group A. Finally, the result that can be considered more interested in current study was the significant decrease of vertical bone loss around mini-implants in group B than in group A during each interval of study. Conclusion: Posterior support by short implants can be considered an advantageous concept regarding preservation of the alveolar bone around mini-implants used for retaining mandibular complete overdenture.