Background The sustainability of programmes and interventions is more rarely studied than initial implementation. The aim of this study was to investigate, from a sustainability perspective, the implementation of an extensive decommissioning programme in one of the local health systems in Sweden (a so-called region). Decommissioning may become increasingly relevant because health systems today face many challenges that increase the pressure on existing resources.Methods Interviews were performed with 26 clinic managers 3 years after initial implementation of a decommissioning programme. The analysis was based on a model of potential influences on sustainability by Wiltsey Stirman et al.Results Initial adoption was possible due to the involvement of the clinic managers in developing the programme, which comprised everything from closed and merged units to formalised admission criteria, altered prescription patterns and changed patient pathways. Conditions for sustainability were created by changed and intensified meeting structures that resulted in learning networks and through the clinic managers’ central role balancing the staff’s claims while trying to execute the region leadership’s demands. Factors working against sustainability were, among others, fragmented support from the health system’s central functions for HR and economy, altered local conditions with an escalating staffing crisis, too few follow-ups and a decline in the strategic leadership over the years.Conclusions We conclude that the programme was partly sustained and that the most important influences were intervention fit and modifications (i. innovation characteristics), clinic and health system leadership (ii. context), workforce and champions (iii. capacity) and shared decision-making and relationship building (iv. processes and interactions). Perhaps most important for sustainability was the continuous attention to the health system’s poor economy, visible via a great effort by the clinics to keep their budgets—a change in the culture at the clinics. Furthermore, the study shows that, although unpopular, there are also positive effects of decommissioning from the perspective of the primary implementers, e.g., opportunities to make difficult but necessary changes and increased collegial support when centralising services.