Diffusion Weighted Imaging (DWI) represents a recent added value to conventional MRI. It is applied in many oncological diseases, improving detection of lesions and possibility of tissue characterization. Quantitative measurement – obtained calculating the Apparent Diffusion Coefficient (ADC) – has been proposed to better characterize the vitality of the oncological tissue. Head and Neck Squamous Cell Carcinoma (HNSCC) are predominantly diagnosed in advanced stage; subsequently, radiotherapy and chemotherapy are generally adopted at the beginning of treatment to reduce stage of disease. The changes in a tumour lesion are not easily assessed by conventional approaches, which are currently based on morphological features. Therefore, the role of diffusion MRI in the management of head and neck cancer has been proposed to early identify response to treatment. In addition, DWI capability in the assessment of nodal involvement and in the evaluation of residual/recurrence of disease after therapy is briefly discussed, explaining advantages due to its application in the management of HNSCC.