This paper provides an overview of recent developments in big data in the context of biomedical and health informatics. It outlines the key characteristics of big data and how medical and health informatics, translational bioinformatics, sensor informatics and imaging informatics will benefit from an integrated approach in piecing together different aspects of personalized information from a diverse range of data sources, both structured and unstructured, covering genomics, proteomics, metabolomics, as well as imaging, clinical diagnosis, and long-term continuous physiological sensing of an individual. There is great hope that recent advances in big data will expand our knowledge for testing new hypotheses about disease management, from diagnosis, to prevention to personalized treatment. However, it also raises challenges in terms of privacy, security, data ownership, data stewardship and governance. This paper discusses some of the existing activities and future opportunities related to big data for health, outlining some of the key underlying issues that need to be tackled.