We investigated the functional outcome in patients who underwent reverse shoulder replacement (RSR) after removal of a tumour of the proximal humerus. A total of 16 patients (ten women and six men) underwent this procedure between 1998 and 2011 in our hospital. Five patients died and one was lost to follow-up. Ten patients were available for review at a mean follow-up of 46 months (12 to 136). Eight patients had a primary and two patients a secondary bone tumour. At final follow up the mean range of active movement was: abduction 78° (30° to 150°); flexion 98° (45° to 180°); external rotation 32° (10° to 60°); internal rotation 51° (10° to 80°). The mean Musculoskeletal Tumor Society score was 77% (60% to 90%) and the mean Toronto Extremity Salvage Score was 70% (30% to 91%). Two patients had a superficial infection and one had a deep infection and underwent a two-stage revision procedure. In two patients there was loosening of the RSR; one dislocated twice. All patients had some degree of atrophy or pseudo-atrophy of the deltoid muscle. Use of a RSR in patients with a tumour of the proximal humerus gives acceptable results. Cite this article: Bone Joint J 2013;95-B:1551–5