Silent sinus syndrome (SSS) is a quite rare clinical entity characterized by unilateral enophthalmos and hypoglobus secondary to thinning and inward bowing of the maxillary sinus roof in the absence of signs or symptoms of intrinsic sinonasal inflammatory disease. We present a case of a 16-year-old female with a 10-month history of facial asymmetry due to swelling of the left cheek and ptosis of the left eye with no other symptoms. Computed tomography scans and Water's x-ray revealed an opacified left maxillary antrum with characteristic features of SSS. The patient underwent surgery and a thick maxillary sinus mucocele was found and enucleated successfully during the operation. Six-month and 2-year follow-ups after surgical treatment revealed satisfactory results and there was no need for reconstruction of the orbital floor. Although patients with SSS often initially present to ophthalmologists, oral and maxillofacial surgeons and radiologists should be familiar with this phenomenon since most of these patients will be referred to dental hospitals for further treatment.