All post-Soviet countries are trying to reform their primary health care (PHC) systems. The success to date has been uneven. We evaluated PHC reforms in Estonia, using multimethods evaluation: comprising retrospective analysis of routine health service data from Estonian Health Insurance Fund and health-related surveys; documentary analysis of policy reports, laws and regulations; key informant interviews. We analysed changes in organisational structure, regulations, financing and service provision in Estonian PHC system as well as key informant perceptions on factors influencing introduction of reforms. Estonia has successfully implemented and scaled-up multifaceted PHC reforms, including new organisational structures, user choice of family physicians (FPs), new payment methods, specialist training for family medicine, service contracts for FPs, broadened scope of services and evidence-based guidelines. These changes have been institutionalised. PHC effectiveness has been enhanced, as evidenced by improved management of key chronic conditions by FPs in PHC setting and reduced hospital admissions for these conditions. Introduction of PHC reforms - a complex innovation - was enhanced by strong leadership, good co-ordination between policy and operational level, practical approach to implementation emphasizing simplicity of interventions to be easily understood by potential adopters, an encircling strategy to roll-out which avoided direct confrontations with narrow specialists and opposing stakeholders in capital Tallinn, careful change-management strategy to avoid health reforms being politicized too early in the process, and early investment in training to establish a critical mass of health professionals to enable rapid operationalisation of policies. Most importantly, a multifaceted and coordinated approach to reform - with changes in laws; organisational restructuring; modifications to financing and provider payment systems; creation of incentives to enhance service innovations; investment in human resource development - was critical to the reform success.