The aim of this investigation was to determine the long-term clinical outcome and predictability of the maxillary sinus augmentation procedure utilizing a variety of bone augmentation materials. The augmentation materials evaluated were a xenograft alone (Bio-Oss), an alloplast alone (Interpore), a xenograft-alloplast combination (Bio-Oss mixed with Interpore in a 1:1 ratio), an alloplast (Interpore) mixed with autogenous bone from the iliac crest (in a 1:3 ratio), and an alloplast (Interpore) mixed with autogenous bone from the chin (in a 1:1 ratio). A total of 340 plasma-sprayed cylinder implants (IMZ) were placed, either simultaneously with the sinus augmentation procedure (235 implants), or 6 months after the procedure (105 implants) in 133 patients with insufficient bone volume in the posterior maxilla. The implants were restored with a total of 151 fixed detachable ceramometal prostheses and evaluated up to a 5-year period. Clinical evaluations included yearly assessments of peri-implant inflammation, implant mobility, and clinical attachment levels. Radiographs were also taken prior to sinus augmentation surgery, at abutment connection, at completion of the restoration, and thereafter at yearly intervals. All of the implants placed into the augmented sinuses achieved osseointegration. Only four implants (1.2%) failed to maintain osseointegration after prosthesis placement, yielding an implant survival rate of 98.8% during the entire course of the study. Of the 340 implants, 307 (90.3%) were considered successful according to the success criteria used. Gender, implant length and location, remaining bone height, and type of bone augmentation material had no effect on implant success. None of the 151 prostheses was lost during the observation period. The results of this study support the long-term clinical predictability of maxillary sinus augmentation procedures for the rehabilitation of the edentulous posterior maxilla with implant supported prostheses. Keywords: dental implant, implantology, oral surgery, prosthodontics, sinus augmentation