Congenital parasitic conjoined twin is an unusual parasite of the asymmetrical duplication in otolaryngological field, especially it's involvement of the maxilla is very rare. Recently, the author experienced a case of congenital parasitic conjoined twin which developed from the left maxilla of a new born. The adult fist sized parasitic mass was removed surgically and it's histopathological diagnosis was a parasitic conjoined twin.