The purpose of this study was to examine the most frequently used criteria to define treatment success in implant dentistry. An electronic MEDLINE/PubMED search was conducted to identify randomized controlled trials and prospective studies reporting on outcomes of implant dentistry. Only studies conducted with roughened surface implants and at least five-year follow-up were included. Data were analyzed for success at the implant level, peri-implant soft tissue, prosthetics, and patient satisfaction. Most frequently reported criteria for success at the implant level were mobility, pain, radiolucency, and peri-implant bone loss (> 1.5 mm), and for success at the peri-implant soft-tissue level, suppuration, and bleeding. The criteria for success at the prosthetic level were the occurrence of technical complications/prosthetic maintenance, adequate function, and esthetics during the five-year period. The criteria at patient satisfaction level were discomfort and paresthesia, satisfaction with appearance, and ability to chew/taste. Success in implant dentistry should ideally evaluate a long-term primary outcome of an implant-prosthetic complex as a whole.