Temporomandibular joint (TMJ) ankylosis is an intracapsular union of the disccondyle complex to the temporal articular surface that restricts mandibular movements, including fibrous adhesions or bony fusion between the condyle, disc, glenoid fossa, and articular eminence. The leading causes include trauma and infection. It can be a serious and disabling condition that leads to difficulties in mastication, swallowing, speaking, esthetics and oral hygiene. Disturbances of facial and mandibular growth and acute compromise of the airway invariably result in physical and psychological disability. Treatment should be initiated as soon as the condition is recognized, with the main objective of re-establishing joint function and harmonious jaw function. The purpose of this report is to describe a case of unilateral fibrous ankylosis of the right TMJ in a three-year-old girl.