Primary intraosseous squamous cell carcinoma of jaw is a rare tumour. It arises from the lining of an odontogenic cyst or de novo from postulated odontogenic cell rests and is rarely diagnosed by FNAC. The primary intraosseous carcinoma of squamous cell origin is very infrequent and only few cases are reported in available literature. The following case report describes a case of primary intraosseous squamous cell carcinoma of mandible in a 45 year old male patient with emphasis on cytological features. The main purpose is to highlight diagnostic significance of FNAC for rapid and accurate diagnosis of lesions of mandible and unusual clinical presentation.