A consensus Development Conference was held at the National Institutes of Health from September 29-October 1, 1980, to address issues concerning the role of carcinoembryonic antigen (CEA) as a marker in the management of cancer. The panel met following formal presentations and discussions to assess the issues based on the evidence presented. These issues included: Should CEA be used in cancer screening? Is CEA helpful in cancer diagnosis? What does CEA tell about the extent and outcome of cancer? Is CEA helpful in monitoring cancer treatment? This paper constitutes the panel's findings.