Objectives : To compare the influence of platform switched and matched implants on supporting structures of mandibular overdenture by measuring marginal bone loss (MBL) and soft tissue changes including probing depth and implant stability. Material and Methods: Twenty completely edentulous patients age 50-60 years were selected for this longitudinal study. Complete dentures were performed for all patients, they were divided randomly into 2 groups; 10 patients each. The first group obtained 2 platform switched implants while the second group obtained two platform matched implants (3.6 × 11.5 mm) in the canine areas of the mandible. Radiographic measures were performed every 12 months for 3 years while clinical measures were made every 6 months for 3 years for each group. Data was examined by student's t-test and paired t-test. Results: The mean age of patients was 54 ±3.3 years. No statistically significant difference was observed in MBL between mandibular overdentures supported by 2 platform switched and that supported by 2 platform matched implants (p≥0.05). Also, there were no statistically significant differences in pocket depth or implant mobility between two studied groups after 1, 2 and 3 years follow up (p≥0.05). Conclusions: Platform switching appears to not influence marginal bone loss around implants or soft tissue in two implants supported mandibular overdentures.