Mucormycosis is a rare and fulminating opportunistic fungal infection that occurs almost in immunocom-promised patients. It is also a highly virulent and rapidly progressive disease with poor prognosis. Its incidence has been increasing in recent years. We have experienced a case of solitary duodenal mucormycosis in a 45 year-old male patient. Mucormycosis was diagnosed by pathology & culture and he was treated with amphotericin B and discharged with clinical improvement. We report this case with a literature review. (Korean J Gastrointest Endosc 2000;20:303-306)