Oral squamous cell carcinoma is the third most common cancer in Indian subcontinent affecting people with lower socioeconomic status. Due to inadequate screening facilities and lack of awareness among individuals most of the oral cancer cases are detected at an advanced stage. As early stage oral squamous cell carcinoma patients can be treated with single modality treatment (surgery or radical radiotherapy), multimodality regimen (surgery followed by concurrent chemoradiation) is adopted for high risk advanced stage cancers with multiple adverse features like extra nodal extension, lymphovascular invasion and perineural spread. The chapter outlines the principles of adjunctive therapy in oral cancer patients with special reference to different techniques, indications of radiotherapy and role of chemotherapeutic regimes in improving the overall survival of advanced stage oral cancer patients.