The Nordic countries have individually and jointly identified the potential of secondary use of health data in research, health care and innovation. There is a need to enhance data quality and interoperability and make data machine-readable in order to lay the foundation for open science and innovation. Obstacles that impede data sharing such as legal, technical and procedural bottlenecks must be removed. This NordForsk report proposes a step-wise implementation of a Nordic Commons for health data building on national efforts. It would allow expansion to the Nordic level, with data more easily identified, shared, compiled and jointly analysed, and would give the Nordic region a competitive advantage. The Nordic Commons will provide a platform for conducting reproducible and open research for the benefit of Nordic public health and societies. The report includes suggestions for policy implications with specific recommendations directed towards the key actors required to implement a Nordic commons, e.g. the Nordic policy level, research and innovation funders, and data owners. Careful, coordinated and concrete actions are called for by all of these actors to realise the Nordic commons.