Purpose: The objective of this systematic review was to present the current scientific and clinical evidence related to implant-supported rehabilitations for the edentulous mandible and maxilla. Materials and Methods: An electronic search of several databases covered the period from January 1966 to August 2008. From a total of 2,371 publications identified from this search, 61 articles fulfilled the inclusion criteria set forth by the authors. It should be noted that only studies reporting on implants with rough surfaces were included in the final selection for this review. Results: Selected studies yielded data from 2,278 patients and 9,701 implants. Studies were grouped according to treatment protocol and prosthodontic design, and results on conventional, early, and immediate loading were assessed separately for fixed and removable dental prostheses. Clinical recommendations for implant loading in different edentulous indications were established using a special validation protocol of the published scientific and clinical evidence for different treatment modalities, which was based on the study design, sample size, and outcome homogeneity between studies. Conclusions: The highest level of scientific and clinical validation was found for conventional loading with mandibular overdentures and maxillary fixed dental prostheses. Insufficient scientific or clinical documentation/validation was found for immediate loading of maxillary overdentures, as well as for immediate loading of immediately placed implants combined with fixed or removable dental prostheses in either jaw. All other loading protocols for edentulous arches showed different degrees of clinical documentation. Keywords: dental implants, edentulism, fixed dental prosthesis, loading protocol, mandible, maxilla, removable prosthesis, systematic review