Introduction: The enophthalmos may be caused by many pathological processes that involve the orbital floor. The spontaneous asymptomatic enophthalmos, not related to trauma or previous sinus surgery, constitute a constellation of features known as Silent Sinus Syndrome, a rare condition, first described in 1964. Objective: To describe a case of Silent Sinus Syndrome discussing probable pathophysiological mechanisms, diagnosis and treatment. Case report: A patient with Silent Sinus Syndrome was submitted to a functional endoscopic sinus surgery, in which uncinectomy and maxillary antrostomy were performed. In a 4-month follow-up, the enophthalmos was improved. Conclusion: Otolaryngologysts should know the Silent Sinus Syndrome and that functional endoscopic sinus surgery is efficient in its treatment.