Material and method– This case report considers a 10 year old female, who reported with chief complaint of reduced mouth opening i.e 12mm. On radiographic examination bony mass was seen on sigmoid notch. CBCT revealed unilateral pseudoankylosis of right side of mandible. Based on extra–oral examination and radiographic examination treatment plan was made i.e removal of bony mass. Then excision of bony mass was done under GA and satisfactory mouth opening was achieved and physiotherapy was advised to the patient and follow up was done. On 6 month post op, the mouth opening is 33mm Conclusion– Pseudoankylosis can occur by trauma, radiation and infection. We can lower the incidence by early physiotherapy. In some cases we can treat it by forceful mouth opening and in certain cases we can treat it by removing the mass.