Preoperative and postoperative carcinoembryonic antigen (CEA) levels were evaluated in 42 patients with colorectal carcinoma. Preoperative CEA values correlated inversely with survival at a statistically significant level and provided prognostic information not available by pathologic staging. Postoperative plasma CEA can accurately predict recurrent disease and may, when serial values are elevated, serve as an indication for a second-look procedure.