The over expression of LL37, an antimicrobial peptide belonging~to the cathelicidin family has implication in the progression of human malignancy but the exact role is still not clear. This study aims to elucidate the correlation of LL37 with Head and Neck Squamous Cell Carcinoma (HNSCC) and the consequences of radiotherapy on it. The LL37 levels were quantified in serum samples of control and HNSCC patients at pre-RT, during-RT and post-RT using a real time Surface Plasmon Resonance technology and ELISA. The LL37 of 50 HNSCC patients was significantly (p < 0.0001) threefold higher than the 25 controls and declined with respect to radiation therapy (p < 0.0001) supporting its candidature as a prognostic marker in HNSCC.