The immunohistochemical localization of lactoferrin (LF) was investigated in the duodenojejunal mucosa of children with untreated and treated celiac disease and in a control group of children of short stature and of children with postenteritis syndrome. In subtotal villous atrophy, LF was present in all epithelial cells of the luminal surface with a lower degree of positivity in crypts, whereas a variable degree of reactivity for LF was observed in epithelial cells of reconstituted villi and crypts. The LF mucosal distribution, however, was not specific for celiac disease since the LF pattern was similar in untreated celiac disease and also in postenteritis syndrome. Moreover, LF was detectable only in 7 of 18 duodenojejunal juice samples obtained from untreated and treated celiac patients and normal controls, the observed values being irrespective of the mucosal morphological status. We conclude that the immunohistochemical evidence of LF in the enterocyte may derive from an autochthonous production since our histochemical findings cannot be related to the concentration of LF in duodenal juice.