An increased prevalence of chronic gastritis has been reported in patients with chronic Chagas' disease (American trypanosomiasis), which is regarded to be model of intrinsic denervation of the gastrointestinal tract. In order to investigate whether this condition is associated with a reduction of prostaglandin levels in gastric mucosa, we studied 14 Chagas' disease patients with megaesophagus and/or megacolon and compared them with 10 control subjects. All patients and controls underwent an upper gastrointestinal tract endoscopy where biopsies were collected from the antrum for histology and for 6-keto-PGF 1 alpha radioimmunoassay. In the Chagas' disease group, the proportion of patients with either moderate or severe gastritis (7/14) was significantly higher (p < 0.01) than in the control group (0/10). Values for antral 6-keto-PGF 1 alpha in Chagas' disease patients (median: 80.75 ng/g; range 36.5-245.6 ng/g) were slightly lower than those obtained in controls (median: 116.2 ng/g; range: 13.1-269 ng/g), but the difference was not statistically significant (p > 0.10). These results confirm previous observations suggestive of an increased prevalence of chronic gastritis in Chagas' disease, but do not support the view that chronic destruction of the intramural neurons of the gut, which is known to occur in this condition, is associated with a reduction of prostaglandin levels in gastric antral mucosa.