PURPOSE: To perform a systematic review on studies assessing clinical outcomes in patients rehabilitated with complete-arch fixed implant-supported prostheses according to the time of loading. MATERIALS AND METHODS: Data obtained from patient and clinical outcomes, as implant failure, success rate, survival rate, biological complications, technical complications, mechanical complications, and marginal bone loss, were included on this review. The search was performed on databases PubMed, Scopus, and Cochrane. Cochrane Collaboration tool was used to assess the risk of bias of randomized controlled studies, and an adapted version of Newcastle-Ottawa scale was used for observational studies. All data were tabulated according to the time of loading: (1) immediate restoration/loading, (2) early loading, and (3) conventional loading. RESULTS: From a total of 4027 studies identified through the three databases, six of them were randomized controlled trials, five of them were prospective observational studies, and another five were retrospective observational studies. In total, 5954 implants, 1294 patients and 1305 full-arch fixed implant-supported prostheses were included in this review. There was a wide heterogeneity among clinical studies regarding the study design and treatment procedures. Thus, pooled estimates were not performed in order to avoid potential biases. The methodological assessment by the Modified Newcastle-Ottawa scale showed a moderate quality of observational studies. Regarding the RCTs studies, all of them presented at least one element of bias according to the Cochrane Collaboration tool for assessing risk of bias. CONCLUSION: There is evidence of high survival-success implant rate (95-100%) for either loading protocols (immediate restoration/loading, early loading, and conventional loading). However, careful attention must be taken by clinician when interpreting the results reported in clinical studies. Future studies should be performed using standardized methodology in order to determine the true predictability regarding immediate, early, and conventional loading protocols.