Purpose: To evaluate the long-term clinical performance of prosthetic reconstructions on one-piece implants, with a focus on technical and biological complications. Materials and Methods: An electronic MEDLINE search complemented by a manual search was conducted to identify randomized and prospective controlled clinical trials on one-piece implants. Additional inclusion criteria were a mean follow-up period of at least 5 years and an inception cohort where more than 80% of the enrolled patients remained in the study at the 5- or 10-year observation point. Results: Sixty-six studies from an initial yield of 597 titles were selected, and the data were extracted. Of the full-text articles examined, 46 were excluded and a total of 20 articles were finally selected. All studies were published between 1995 and 2011. Two different study designs were identified: 4 randomized controlled trials and 16 prospective cohort studies. The studies were analyzed and classified according to study type, patient characteristics, prosthetic characteristics, and biologic and technical complications after 5 and 10 years. The meta-analysis of the included studies showed a prosthetic survival rate for one-piece, one-part implants of 82.81% after 5 years and 97.85% and 98.24% in two-part implants after 5 and 10 years, respectively. Although the prosthetic survival rates were high, complications were frequent: complications of the suprastructure (18.44% to 18.75%), screw loosening/fracture (7.64%), soft-tissue complications (4.69% to 8.25%), sensory disturbances (0.36% to 6.25%), implant loss before loading (0% to 0.23%) and during function (1.10% to 3.21%), and implant fracture (0.0004%). Conclusion: Within the limits of this systematic review, it can be concluded that despite high long-term prosthetic survival rates, technical and biologic complications are frequent in one-piece implants, both in one-part and two-part designs. Further randomized clinical trials are needed to provide more information about the outcome of different variables associated with this type of implant design.