The delivery of health care is undergoing dramatic change. Often, patients have come to be viewed as customers and physicians as merely providers. The progressive rise in the cost of medical care has placed a premium on restraint. Unfortunately, quality has not received the same emphasis. As costs equalize among health care systems, however, quality of care will become the major differentiating feature among providers, including gastroenterologists. These changes have lead to what some term the third revolution in medical care, that is, "assessment and accountability". The field of outcomes research has emerged in response to these influences, providing the means to measure the relative effectiveness of different interventions to identify those that provide the most benefit for their cost. At the same time, outcomes research provides a monitoring system to ensure that quality is not sacrificed in the enthusiasm to reduce expenditures. These principles have implications in the practice of clinical gastroenterology.