Introduction: In Head and neck squamous cell carcinoma (HNSCC), the clinical assessment of mandibular involvement is often inaccurate and unreliable. Involvement of mandible, upstage the disease to stage IV. Investigations like orthopantogram, computed tomography (CT), magnetic resonance imaging (MRI), bone scintigraphy etc have been evaluated by different authors for involvement of mandible with wide variation in results. This has prompted us to correlate clinically, radiological, and pathological to formulate the appropriate protocol for evaluation of mandibular involvement. Materials And Methods: It is a prospective and a retrospective study. In prospective part, all patients with clinical and radiological confirmation of mandibular involvement were undergone mandibulectomy. The histologic findings of mandibular bone involvement were then compared with the radiographic findings, along with tumor location, stage, and grade. For retrospective study, the medical records of patients, who had under gone mandibulectomy as a part of treatment of oral cavity cancers were analyzed and correlated. Results: In the present study, the bone involvement was found in 69% clinically, 40.5% by Orthopantogram, 39.6% by CT scan and 54% on MRI scan. The histological confirmation of bone involvement was evaluated in all the above cases. It was found that 22% of clinically positive, 46% of OPG positive patients, 52% of CT scan positive and 46% of MRI positive had invasion Conclusion: There is no single modality of investigation which appears to have high specificity and sensitivity. Combination of different modalities increases the both sensitivity and specificity. In our study clinical examination along with high resolution CT scan has the acceptable sensitivity and specificity which may be applied for better results.