Abstractobjectives To identify factors affecting the implementation of large-scale programmes to optimise the health workforce in low-and middle-income countries.methods We conducted a multicountry case study synthesis. Eligible programmes were identified through consultation with experts and using Internet searches. Programmes were selected purposively to match the inclusion criteria. Programme documents were gathered via Google Scholar and PubMed and from key informants. The SURE Framework -a comprehensive list of factors that may influence the implementation of health system interventions -was used to organise the data. Thematic analysis was used to identify the key issues that emerged from the case studies.results Programmes from Brazil, Ethiopia, India, Iran, Malawi, Venezuela and Zimbabwe were selected. Key system-level factors affecting the implementation of the programmes were related to health worker training and continuing education, management and programme support structures, the organisation and delivery of services, community participation, and the sociopolitical environment.conclusions Existing weaknesses in health systems may undermine the implementation of largescale programmes to optimise the health workforce. Changes in the roles and responsibilities of cadres may also, in turn, impact the health system throughout.