BACKGROUND: The difference between 'policy as promised' and 'policy as practiced' can be attributed to implementation gaps. Actor relationships and power struggles are central to these gaps but have been studied using only a handful of theoretical and analytical frameworks. Actor interface analysis provides a methodological entry point to examine policy implementation and practices of power. As this approach has rarely been used in health policy analysis, this article aims, first, to synthesise knowledge about use of actor interface analysis in health policy implementation and, second, to provide guiding steps to conduct actor interface analysis. METHODS: We conducted an interpretive synthesis of literature using a set of 6 papers, selected using purposeful searches and focusing on actor dynamics and practices of power in policy experiences. Drawing upon the framework synthesis approach and using a guiding framework, the synthesis focused on 4 questions - the type of actor interfaces formed, the power practices observed, the effect of such power practices on implementation and the underpinning factors for the power practices. RESULTS: Multiple interface encounters and power practices were identified which included domination, control, contestation, collaborations, resistance, and negotiations. The lifeworlds of actors that underpinned the power practices, were rooted in social-organisational power relationships, personal experiences and interests, and social-ideological standpoints like values and beliefs of actors. The power practices influenced implementation both positively and negatively. CONCLUSION: Based on the learnings from synthesis, this paper provides guiding steps for conducting actor interface analysis. Additionally, it presents 2 useful tools for power analysis: (1) 'actor lifeworlds,' to understand underpinning factors for power practices and (2) relationships of lifeworlds, interface encounters and power practices with their effect on policy implementation. We suggest that interface analysis should be applied in more empirical settings and across varied health policy experiences to nuance the method better.