This article explores how promises are forged in the emerging techno-scientific field of ‘personalized health’ (PH) in Switzerland and how they challenge the research-healthcare boundary when dealing with issues of ethical acceptability. Switzerland provides a relevant location in which to examine these questions as PH has emerged in this context with the specific connotation of improving health in the population as a whole, through the development of a data infrastructure to enable nationwide accessibility and sharing of health-related data. Drawing on our analyses of discourses and practices of scientific and institutional actors, we show that the development of PH in Switzerland is the result of ethical boundary work aimed at enrolling local biomedical institutions, heterogeneous groups of professionals, as well as the general public in nationwide research initiatives with important implications for healthcare and the healthcare system.