Precision medicine aims to combine comprehensive data collected over time about an individual's genetics, environment, and lifestyle, to advance disease understanding and interception, aid drug discovery, and ensure delivery of appropriate therapies. Considerable public and private resources have been deployed to harness the potential value of big data derived from electronic health records, 'omics technologies, imaging, and mobile health in advancing these goals. While both technical and sociopolitical challenges in implementation remain, we believe that consolidating these data into comprehensive and coherent bodies will aid in transforming healthcare. Overcoming these challenges will see the effective, efficient, and secure use of big data disrupt the practice of medicine. It will have significant implications for drug discovery and development as well as in the provisioning, utilization and economics of health care delivery going forward; ultimately, it will enhance the quality of care for the benefit of patients.