Fungal infection of maxillary sinus was a rare disease, but it has increased tendency with overuse of antibiotics, steroid hormones, and anticancerous agents. The authors are reporting two cases of aspergillosis of maxillary sinus. Case 1 : A 61-year-old female patient had suffered from foul odor bloody mucopurulent rhinorrhea, posterior nasal dripping, left cheek pain and frontal headache. Hemorrhagic polyp in left middle meatus and swelling of left cheek were seen. P.N.S. Water's view showed that homogenous increased density was visible in left maxillary sinus, ethmoid sinuses and frontal sinus without bony destructive change. Caldwell-Luc's operation and mucosal biopsy revealed aspergillosis. Case 2 : A 46-year-old male patient complained of mucopurulent rhinorrhea, right facial and temporal pain for three months. Swelling and reddness in right middle turbinate and brownish mucopurulent disoharge in Rt. miue meatus were seen. P.N.S. Water's view showed total haryness and distinct bone margin on right maxillary antrum. Chronic suppurative maxillary sinusitis was suspected, but Caldwell-Luc's operation with mucosal biopsy revealed aspergillosis. The authors emphasize the symptom, and sign of mycotic invasion in paranasal sinuses may duplicate early malignancy of this area and chronic suppuative maxillary sinusitis.