Acute mucositis is the main intensity-limiting toxicity in the management of head and neck (H&N) and digestive track carcinomas with radiotherapy. New radiation modalities (hyperfractionation and/or acceleration) as well as combined modality regimens in this situation induce higher rates of acute toxicity. Hyperfractionation for example allows higher control rates, with few late toxicities, but it slightly increases acute mucositis. The addition of chemotherapy introduces systemic toxicity and can exacerbate local tissue reactions when used concurrently with radiation. Mucositis is recognized as the principal limiting factor to further treatment intensification. As local-regional control and overall survival are related to dose-intensity in this case, further research into the assessment, analysis, prevention and treatment of mucosal toxicity is not only crucial to the improvement in quality of life, but certainly to improved rates of disease control as well. Several topical and systemic treatments are directed to the decrease and the acceptance of this acute toxicity, but few have shown significant preventive effect. Improvement of technical aspects of H&N radiotherapy (3D conformal radiation, intensity-modulated radiotherapy) should have a major impact in the prevention of mucositis. The efficacy of low level laser therapy in the management of such a toxicity could hence yield important development of this method in the field of oncology. MASCC/ISOO mucositis group's recommendations for the management of acute radiation-induced mucositis are here summarized.