The number of patients with maxillary sinus mycosis has recently been increasing, but to diagnose the preoperatively it is not always easy and the causative factors have not yet been clarified. In this study, 10 cases (3 men and 7 women) of maxillary sinus mycosis treated in our hospital between 1994 and 1998 were reviewed to clarify the clinical characteristics of maxillary sinus mycosis. Six cases were diagnosed as aspergillosis by pathological examination, and another as candidasis. The fungus was not identified the other 3 cases. Radiological examination revecked ostiomeatal obstruction or stenosis and nasal septum deviation in seven cases. Radical antrostomy of the maxillary sinus was performed in 5 cases, functional endoscopic sinus surgery in four cases, and conservative treatment by nasal or antral irrigation in the other cases. All patients were completely cured, and no recurrences have been observed. Based on these findings, a surgical approach to restore ventilation of the maxillary sinus appears to be important in the treatment of maxillary sinus mycosis.