Diarrhea is one of the important clinical symptoms in patients suffering from celiac disease and is attributed mainly to malabsorption. We determined prostanoid content in small intestinal mucosa of five patients with active celiac disease and in a control group consisting of six patients. Prostaglandin E2 and thromboxane B2 content in duodenal mucosa of patients with active celiac disease was 1,581 +/- 161 and 118 +/- 40 pg/mg wet wt, respectively, significantly higher than their content in duodenal mucosa of the control group, 378 +/- 86 and 8 +/- 8, p less than 0.001 and p less than 0.02, respectively. 6-Ketoprostaglandin F1 alpha content in celiac patients was not significantly different from its content in the control group: 908 +/- 437 and 124 +/- 53 pg/mg wet wt, respectively. It is possible that, in celiac disease, increased mucosal prostanoid content may contribute, at least in part, to intestinal electrolyte and fluid secretion and consequent diarrhea.