Maxillary sinus is frequently presented as a single space within each maxilla. It drains directly into the nose through the middle meatus. We are reporting the second rare case of a mucocele in a separate compartment of maxillary sinus in a 26-year-old patient without a history of facial trauma. The non-contrast computed tomography of paranasal sinuses showed an expansile right infraorbital cystic lesion developed in an upper lateral position of the maxillary sinus. An excision biopsy was performed, which showed histopathological findings of a maxillary sinus mucocele.