The silent sinus syndrome, also known as imploding antrum and chronic maxillary sinus atelectasis, consists of painless enophthalmos, facial asymmetry with inward retraction of the ipsilateral maxillary sinus walls as seen on imaging studies.  It is a well-recognized entity in the field of otolaryngology, but the syndrome remains relatively unknown among radiologists despite its characteristic radiological features.  The chronic maxillary sinus atelectasis presenting to the Emergency Room with facial trauma, this entity may, to the radiologist unaware of its existence, be misdiagnosed as an orbital floor blowout fracture, especially when the trauma is ipsilateral. Features that distinguish it from the blow-out fracture are the associated deformities of the other maxillary walls, total opacification of the sinus (as opposed to an air-fluid level), and osteolysis of the sinus walls (if present). It can be definitively treated by creating an outlet for mucous drainage from the obstructed sinus, the goal of treatment being to arrest disease progression without development of further deformity. The purpose of this article is to acquaint the reader with the clinical and imaging features of the silent sinus syndrome.