Purpose: To evaluate the causes and risk factors associated with implant removal as observed in a hospital setting over a 20-year timespan to find the most common causes leading to implant removal. Materials and Methods: In the present retrospective study, implants removed between 2000 and 2022 were registered and the cause of removal established. All implants were removed by a single operator (P.P.M.) in the Department of Oral Surgery of the George Eastman Dental Hospital in Rome, Italy. Characteristics of removed implants such as implant surface, morphology (bone- versus tissue-level implants), type of restoration (fixed versus removable), mode of retention in the case of fixed restorations (cement- versus screw-retained), and location of the implant (maxillary versus mandibular) were recorded. Patient-level characteristics were also recorded, including patients’ systemic health conditions, the medications they were currently taking or had taken, smoking habits, and if they had a previous history of periodontitis. Results: In total, 381 implants in 381 patients were removed in the 20-year timespan. The most frequent cause of removal was peri-implantitis (82.4% of implants), followed by implant malposition and loss of osseointegration. Conclusions: The survival time was not affected by the cause of removal, while bone-level implants had a longer survival time versus tissue-level implants. Maxillary implants had a higher prevalence of peri-implantitis compared to mandibular implants.