Aim: Aim of this study is to report a rare case of Ameloblastic Fibro Sarcoma (AFS) of mandible arising as a denovo malignancy and to review the literature with reference to so far reported cases, nomenclature, classification, differential diagnosis and management. Case report: A 14 year old male patient presented with complaints of a painless swelling of left side of the face since 1 year. Based on clinical presentation and investigation reports it was diagnosed as a case of AFS in left side of mandible arising as a denovo malignancy. He underwent left hemimandibulectomy __ampersandsignlsquo;en bloc__ampersandsignrsquo; with part of the adjacent masseter and pterygoid muscles under general anaesthesia. Discussion: Ameloblastic Fibro Sarcoma (AFS) is one of the rare histopathology variety of odontogenic tumours. The first case of AFS was reported in 1887 by Heath. Since then only 91 cases have so far been reported. This number includes both denovo and sarcomatous transformation from pre-existing ameloblastic fibroma, occurring in different sites. The most common site affected is mandible [78%]. The mean age of patients with tumours arising denovo is 22.9 years. Ours is a case of AFS arising as a denovo malignancy in left side of mandible. Conclusion: We are presenting our case due to rarity and the limited information that exists regarding histopathology characteristics of AFS, lack of defined criteria for grading and biologic behaviour of these tumours, making the diagnosis eluding, treatment decision challenging and assessment of prognosis difficult.