A primary intraosseous carcinoma (PIOC) arising de novo in the mandible is presented. A 50-year-old patient came for help with persistent pain and swelling over left mandibular area for months. After systemic evaluation, ablation and reconstruction surgery was performed. The final diagnosis of PIOC was made. This is an uncommon lesion and is seen essentially in the jawbones. While the majority of the reported cases of PIOC arise from the odontogenic cysts, those arising de novo are infrequently illustrated. The early lesions are either asymptomatic or painful selling. Thus delay of diagnosis or treatment is quite often. Like other malignancies, metastasis to regional lymph nodes or distant organ is observed in advanced PIOC.