The widespread adoption of electronic medical records has created new opportunities for clinical investigation using big data techniques. The potential for nuanced investigation across a full range of clinical questions is tremendous, contingent on the investment hospitals and health systems can make in big data infrastructure. Secondary analysis of electronic health records will enable the use of real patient data to assist clinical decision-making, with the goal of eventually providing near-real time support for bedside encounters. Clinicians and patients will derive value from data-driven decision making, while hospitals and health systems may see returns in quality, patient safety, and satisfaction. For big data analytics to achieve their potential in clinical medicine, issues of data structure, analytics staffing, funding, and data security will have to be addressed, but the future is bright and fertile for the application of big data to medical care.