Mucormycosis is a fungus infection due to family Mucoracea, with broad nonseptate hyphae which are diagnostic. Mucormycosis is rare but important pathologic entity with rapidly fatal course due to cerebral involvement if treatment delayed. Recent World literature indicate an increase in this disease. Recently we expcrienced one case of Mucormycosis in the maxillary sinus, which was not reported in Korea. A 30 year old female minor suffered from left cheek, nose and periorbital pain for 2 months. Caldwell-Luc's operation was done under the impression of left maxillary sinusitis. Operative findings included atypical cholesteatoma like necrotic material filled in the left maxillary sinus, which was biopsied and proved Mucormycosis. This is the report of the Mucormycosis in the maxillary sinus with the review of Literatures.