Purpose <p>The aim of this study was to assess functional and radiological outcomes of radial head arthroplasty (RHA) compared to open reduction and internal fixation (ORIF) in isolated Mason type-III fractures with a minimum of five years follow-up.</p> Methods <p>This was a retrospective single-center study of closed isolated Mason type-III radial head fractures operated between January 2008 and December 2017. Nineteen patients were included in group RHA and 35 patients in group ORIF. The mean age was 51 years old in group RHA and 41 years old in group ORIF (<i>p</i> = 0.02). Functional and radiological outcomes were evaluated.</p> Results <p>Mean follow up was eight years (range, 5–14). Clinical results and functional scores showed no significant differences, except a better pronation in group RHA (<i>p</i> = 0.04). Two secondary radial head resection or implant removal were performed in each group (<i>p</i> = 0.56) with poor functional outcomes in group ORIF. There was less heterotopic ossification in group RHA (15.8% vs. 42.8%; <i>p</i> = 0.03). Capitulum wear was found in 63% in group RHA against 25.7% in group ORIF (<i>p</i> &lt; 0.05).</p> Conclusion <p>Functional results of RHA and ORIF were comparable for isolated Mason type-III fractures at a mean follow-up of eight years. We recommend to perform RHA for isolated Mason type-III fracture if articular reduction or stability of the fixation is not satisfying.</p> Level of evidence <p>III.</p>