The amount and complexity of health-related data which can be collected growing as breathtaking speed. This ranges from molecular constituents of cells (genomics and epigenetics, proteins, metabolites, etc.) to clinical phenotypes of diseases (imaging, electrophysiology, etc.) and to personal lifestyle and environment (lifestyle tracking, “quantified self”). Increasingly, wearable or embedded devices connected via a networks can provide real time or longitudinal data. Provided these “big health data” are accessible and used effectively for meaningful correlation and association studies, they have great potential for biomedical research and individual health care in the future. Increasingly, biomedical research may reverse the traditional paradigm “from experimental animals to humans” into “from first in humans to validation in animals”. However, using patient and citizen data for research raises a series of technical, scientific, ethical and legal (e.g. data protection) questions which must be addresses carefully. In this session, we will discuss challenges and opportunities in using personal data for health research in the context of the Swiss Personalized Health Network SPHN.