There have been sporadic reports of the organizing hematoma not only in soft tissue but also in brain, spinal cord, lung, and maxillary sinus. Organizing hematoma of the maxillary sinus can also present as a rare solitary benign lesion on unilateral maxillary sinus and bone destruction on CT scanning, indicating that it should be included in the differential diagnosis of unilateral maxillary sinus lesions. There have been only a few reports for organizing hematoma of the maxillary sinus. We present one case of organizing hematoma in unilateral maxillary sinus.