Protein-losing enteropathy was observed in two children with Langerhans' cell histiocytosis (LCH). One patient was an infant with congenital cutaneous lesions; the second child had sigmoid and lymph node infiltration. Electron microscopy and immunohistochemistry confirmed, in both, infiltration of duodenum, skin, and liver by LCH. Gastrointestinal involvement by LCH seldom produces prominent clinical manifestations but indicates widespread multisystem disease. Immunohistochemical and/or ultrastructural features allow definitive diagnosis from mucosal biopsy specimens. Review of the literature of gastrointestinal infiltration by LCH emphasizes its poor prognosis, especially when associated with organ dysfunction.