Dose-painting may increase the chance of cure at minimised radiation-induced toxicity in intensity-modulated radiotherapy (IMRT) for primary head and neck cancer. This could also apply for recurrent and second primary head and neck cancers in previously irradiated volumes. This trial (RIDPAINT) investigates the feasibility of FDG-PET guided radiotherapy using IMRT dose-painting by contours for patients with recurrent and second primary head and neck cancer.