Purpose: The objective of this systematic review and meta-analysis was to assess and compare the marginal bone loss around implants supporting single fixed prostheses and multiple-unit screw-retained prostheses. Materials and Methods: The literature was searched manually and electronically to identify studies in which the marginal peri-implant bone loss around single-implant prostheses and screw-retained multiple-implant prostheses was evaluated radiographically. Two reviewers independently selected the literature and extracted the data. The random-effects method was used to obtain estimates of marginal peri-implant bone loss (means and 95% confidence intervals [CIs]). Results: Of the 2,107 studies identified by a preliminary search, 17 fulfilled the inclusion criteria; 7 were related to single-implant prostheses and 10 to multiple-implant screwretained fixed prostheses. The mean marginal peri-implant bone loss was 0.9 mm (95% CI, 0.49 to 1.32 mm) for multiple-implant screw-retained prostheses and 0.58 mm (95% CI, 0.37 to 0.80 mm) for single-implant prostheses. Conclusion: This indirect comparison provided no evidence to support the assertion that there are differences in marginal peri-implant bone loss between single implant prostheses and multiple screw-retained prostheses. Keywords: meta-analysis, multiple implant-supported prosthesis, peri-implant bone loss, single implant-supported prosthesis, systematic review