Citizens in LMICs experience a range of problems with public and private health services: from poor quality of services to rights violations. In spite of numerous calls and interventions for increased community participation in health, service users and citizens often do not have adequate opportunities to engage with the system about their problems and induce appropriate responses and remedies. Responsiveness to citizens' rights and needs is an essential quality of health systems, and is necessary in order to provide inclusive and accountable services, ensure the social rights of citizens and improve the quality of services. Mechanisms for feedback and response are varied and result in dispersed and sometimes conflicting feedback. These range from conventional facility-based complaints boxes and exit surveys to strategies such as community report cards, social audits, and hotlines. Citizen feedback at community-level has also been sought by implementing health facility committees, intersectoral forums, and community monitoring systems. Growing access to information technology in LMICs has often empowered citizens to raise their concerns through social media, the mainstream press, and even through social protest. Health system responsiveness is gaining global currency as an intrinsic goal of health systems alongside service delivery outcomes, financial fairness and equity. However our current understanding of health system responsiveness is extremely limited, and there is a significant evidence gap about the structure, implementation and effectiveness of citizen feedback and the related response mechanisms about health services currently in place in LMICs. In this study, we aim to address these knowledge gaps by asking: What policies and mechanisms (formal and informal) work for receiving and responding to citizen feedback on health systems in South Africa and Kenya? How can health systems responsiveness be strengthened towards the development of learning, equitable health systems? The proposed study is an interdisciplinary mixed methods study, running from 2018 to 2020. The study will be conducted in three phases, and we will apply several, primarily qualitative methods and tools. The first phase will consist of 'mapping' of policies, feedback mechanisms and pathways for system responsiveness in the study provinces (as well as theoretical and methodological framing relating to responsiveness). Many governments in LMICs are recognising the pressing need to improve health system responsiveness, and both countries in this study have recently implemented significant policy reforms aimed at improving responsiveness to citizen feedback on health services. We will capitalise on this window of opportunity, with the second in-depth phase consisting of case studies in each country, tracking the implementation experience of a particular innovation in this area. The third phase will focus on knowledge translation and cross-country comparison. This project will contribute to a deeper and more systematic understanding of health system responsiveness in South Africa and Kenya, with relevance for other comparable LMICs. By applying an embedded approach to HPSR, it is intended that the research will also have a health system strengthening effect: creating space for reflective practice, strengthening feedback and response within the system, and improving decision-making opportunities for HS leaders. Therefore, this study on responsiveness to citizen feedback should also improve the responsiveness of the health systems in which it is implemented. In each country, we have partnered with policy decision-makers engaged in implementing reforms for greater health system responsiveness, and this study will directly help bring about improvements in these policies. We will also engage with other health system and civil society leaders to identify strategies to strengthen health system responsiveness.