A case of maxillary antrolith caused by fungus ball in a 73-year-old male is presented. Computed tomography showed a calcified mass in the right maxillary sinus. A caseous substance found with fiberscope in the orifice of the right maxillary sinus was examined histopathologically and revealed to be fungus ball. Under the clinical diagnosis of fungal infection of the right maxillary sinus, he was treated surgically. The Fungal culture on Sabouraud agar media was negative. Irrigation of the right maxillary sinus was perlbrmed with PVP-I for three months after the operation. The prognosis was excellent. The calculi were postoperatively examined by PAS-staining, FIE-staining, SEM, TEM and energy-dispersive X-ray analysis (EDX).The marginal region of the calculi was PAS-positive and other regions were PAS-negative. A number of fungal hyphae of 2.5 to 5μm in diameter with dichotomous branching were observed in the marginal region. SEM findings showed a rock-like surface with many small holes. TEM findings showed some cell wall-like structures similar to fungi. Calcium (20.85%), phosphorus (11.84%) and magnesium (1.38%) were detected by EDX.