Purpose: The aim of this randomized clinical trial was to radiographically compare peri-implant marginal bone level changes between immediately loaded implants without the removal of an abutment placed at the time of surgery (IL), delayed loaded nonsubmerged implants (NS), and delayed loaded submerged implants (SI). Materials and Methods: Patients' edentulous sites were randomly allocated to the three groups of implants so that each patient received one implant of each group. Digital periapical radiographs were obtained at baseline as well as three (T1), six (T2), and nine (T3) months after implant insertion. The mesial and distal bone crest levels adjacent to each implant were measured, and the mean values were calculated for each implant at each period. The data were statistically analyzed by repeated measures analysis of variance (ANOVA) and the Tukey test (P .05). Results: The patient sample comprised 15 subjects (13 women and 2 men; mean age: 47.7 years) with partially edentulous sites in the mandibular posterior area. Forty-five implants were inserted (15 IL implants, 15 NS implants, and 15 SI implants). There was no statistically significant difference between the three groups with regard to changes in the marginal bone level during the follow-up period. The study achieved a 93.3% cumulative survival rate for both delayed loaded groups (NS and IS) and a 100% survival rate for the IL group. Conclusion: In the 9-month period following the implants, no statistically significant differences were found between immediately and delayed loaded implants or between submerged and nonsubmerged implants in bone level changes in patients with partial posterior mandibular edentulism. Keywords: bone regeneration, dental implant, marginal bone level, osseointegration