Gastric juice CA 19-9 levels were determined in 23 patients affected by gastric cancer, in 57 patients affected by chronic atrophic gastritis of different severities and in 55 'healthy' controls, undergoing endoscopy for upper gastrointestinal tract symptoms. Increased CA 19-9 levels were documented in chronic atrophic gastritis patients as well as in gastric cancer patients, the difference with respect to controls being statistically significant. However, there was considerable overlap between different groups. In particular, gastric cancer patients had CA 19-9 levels similar to those detected in moderate and severe chronic atrophic gastritis. CA 19-9 correlated with gastric juice pH and CEA concentration. Its values were not influenced by the patients' age or sex. In our opinion CA 19-9 gastric juice determination, although not useful in singling out patients harboring gastric neoplasia, may be used in identifying patients 'at risk' for gastric cancer and who might then be referred for more accurate investigations.