The mean plasma carcinoembryonic antigen (CEA) level was found to be significantly increased in 66 patients with alcoholic liver disease (4.4 micrograms/1) compared with the mean CEA level in 164 healthy blood donors (1.6 micrograms/1, p less than 0.001). Eighteen of the patients (27%) had values above our upper normal values of 5 micrograms/1, compared with 3 of 41 (7%) in a group of patients with non-alcoholic liver diseases. On the other hand, the mean CEA values in the two groups did not differ significantly. The CEA level remained unchanged in patients who continued drinking. However, in 20 patients who stopped drinking, the mean CEA levels dropped significantly from 6.6 micrograms/1 to 3.7 micrograms/1. Concomitant fluctuations were seen in CEA, gamma-glutamyltranspeptidase (gamma-GT), asparate aminotransferase (ASAT), and alkaline phosphatase, although a significant correlation was found only between CEA level and the level of gamma-GT (r = 0.32, p less than 0.02). The correlation between CEA and gamma-GT was best in 41 patients without complicating disorders (r = 0.55, p less than 0.001). CEA was significantly increased in patients with complicating disorders. Much of the increase of CEA in many patients with alcoholic liver disease might be secondary to complicating disorders in the respiratory and/or gastrointestinal tracts. This could possible explain why patients with alcoholic liver disease more often than other patients with benign diseases have elevated CEA.