Head and neck cancer (HNC) is most common in several regions of the world where people consume excessive tobacco and alcohol. Treatments options include surgery, radiation therapy, chemotherapy or a combination Concurrent chemoradiotherapy (CCRT) induced oral mucositis (OM) severely affects oral functions, nutritional status and Quality of Life of Head and neck cancer (HNC) patients. Several modalities have been tried to prevent and treat this complication but none proved to be successful until date. In this book we used Low Level Laser Therapy (LLLT) for the prevention and treatment of CCRT induced OM.