In the year 2000, the Institute of Medicine released a groundbreaking report that indicated that as many as 98,000 Americans die each year as a result of medical errors. This report and others that followed have created interest on the part of patients, providers, and purchasers of health care in ways to improve the quality of health care services in the United States. Although it is clear that the health care system must undergo significant transformation if we are to improve patient outcomes, the means to achieve that transformation are not clear. Several proprietary quality improvement methods have been developed in the manufacturing industry and have been successful in improving quality in that industry. Two of these proprietary methods are Six Sigma and Toyota Production System. Recently, some health care organizations have been attempting to use Six Sigma and Toyota Production System methods to improve the quality of patient care, but evidence for their effectiveness in health care is limited. This paper provides a systematic review of the published literature related to the use of Six Sigma and Toyota Production System in health care and, upon finding an almost complete lack of evidence for their use, considers the changes needed in the design and execution of quality improvement projects in order to be able to publish compelling studies based on the projects.