Aims: The purpose of this study was to quantify the functional outcome of the Aequalis shoulder system. Methods: Pre-operatively, 85 patients were scored using the constant scoring system to assess pain, activity, mobility and strength and adjusted (for age) and modified (excluding strength) scores were calculated. Range of movement (ROM) was assessed using a nominal scale. All patients were regularly followed up and were assessed functionally, using the constant scores and ROM, using a nominal scale Results: Pre-operatively, modified constant score range was 4 – 76 with mean 30.3. ROM was variable but poor overall. Abduction was < 600 in 69% and internal rotation was < ‘hand to buttock’ in 77%. At follow up (range 6 – 60 months, mean 24 months), modified constant score range was 29–126 with mean 74.6. Abduction was > 600 in 76% and internal rotation was > ‘hand to sacrum’ in 77%. No implant has been revised. There have been 2 periprosthetic fractures and 2 implants appear radiologically to be loose. Subjectively, only 6 patients are disappointed with the clinical outcome. Conclusion: The Aequalis shoulder system has been demonstrated to be a reliable implant with up to 5 year follow up. It has a good functional outcome with demonstrable improvement with pain, activity and mobility.