Purpose <p>The aim of this study was to assess the clinical results and the causes of implant failure of press-fit radial head arthroplasty (RHA) in the medium- to long-term.</p> Methods <p>97 consecutive patients treated with a press-fit RHA by a single surgeon were analyzed. According to the type of implant they received there were 56 patients with a bipolar prosthesis and 41 patients with an anatomical prosthesis. At the last follow-up, the patients underwent X-rays and clinical evaluation based on the Mayo Elbow Performance Score (MEPS), the patient-assessed American Shoulder and Elbow Surgeons score-Elbow (p-ASES-E), and the Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH). The causes of reintervention and implant failure were recorded.</p> Results <p>The mean follow-up was 9 years (5–17 years); 24 patients were followed up for longer than 12 years. At the last follow-up, the average flexion, extension, pronation and supination were 139°, 15.2°, 82° and 81.2° in the whole cohort of patients, respectively. The MEPS, QuickDASH and p-ASES-e were 94.3, 6.7 and 93.6, respectively. Four patients underwent reinterventions due to 3 bipolar implant disassembly caused by new traumas and 1 aseptic loosening of an anatomical RHA.</p> Conclusions <p>Both press-fit radial head arthroplasty implants analyzed yielded satisfactory clinical and radiographic results in the medium to long-term in most patients, with a very low incidence of implant-related reinterventions (4.1%). In the absence of a pre-specified non-inferiority framework, no formal equivalence claim between the two implant designs can be made on the basis of the present study.</p> Level of evidence <p>IV.</p>