Due to conflicting reports on the role of CEA measurement in the gastric juice of patients with gastric malignancy, we have assessed gastric CEA levels in a variety of both nonmalignant and malignant lesions of the stomach. The average gastric CEA levels were higher in patients with gastric ulcer and gastric cancer than in healthy subjects and those with duodenal ulcer. In addition, the frequencies of abnormally high values were significantly (P less than 0.001) higher in gastric ulcer or gastric cancer than in healthy or duodenal ulcer groups, whereas there was no difference between gastric ulcer and gastric cancer groups. The evaluation of gastric CEA levels in relation to gastric inflammatory changes leads us to suggest a close relationship between gastric CEA values and the degree of gastric inflammation. Gastric lavage cytology did not provide a sensitive tool for detection of gastric disorders. This study suggests little value for gastric CEA determination in gastric cancer detection. However, we believe the association of rising gastric CEA levels with various types of gastritis justifies measuring gastric CEA to recognize "precancerous" mucosal changes of the stomach.