One of a treatment modality used for head and neck malignancies is radiotherapy. A total curative dose is 50-70 Gy fractioned during a period of 5 to 7 weeks in order to reduce oral complications. Adverse reactions to radiotherapy depend on the age, on the patient’s clinical conditions, the total dose, the volume and area being irradiated, on the fractioning and on the associated treatment. Oral complications can be acute and chronic. Acute complications are mucositis, xerostomia, dysgeusia and oral infections. In most cases they are reversible, and they apear during radiotherapy or closley after. Chronic complications are xerostomia, radiation caries, dysgeusia, trismus, soft tissue necrosis and osteoradionecrosis. They apear months, even years after radiotherapy and they are irreversible and have negative influence on patient quality of life. Because their is no unique treatment protocol for complications in patients who receive radiation therapy for malignant conditions of the head and neck, prevention is essential. Regular oral examinations and care are necessary before, during and after cancer therapy. At least three weeks before cancer treatment, the evaluation should be performed. Adequate communication and planning between the oncology and dental teams can minimize the risk of oral complications. Complications can be prevented, and their for long-term management and close follow-up of patients before,during and after radiation therapy is mandatory.