Jaw tumours in children occur infrequently and diagnosing these lesions and predicting their biological behaviour are difficult. Some of them are not diagnosed correctly at the initial stages as having a neoplasm and are wrongly treated for infections by antibiotic administration. Ameloblastoma is a common and aggressive odontogenic epithelial tumour. It has an aggressive behaviour and recurrent course, and is rarely metastatic. Ameloblastoma represents 1% of all tumours and cysts that involve the maxillomandibular area and about 10% of the odontogenic tumours. We are presenting a case report of a large and aggressive tumour in a 9 year old young female patient who was diagnosed as plexiform Ameloblastoma and was managed by hemi mandibulectomy and reconstructed with condylar recon plate and free iliac crest bone graft