Photodynamic therapy (PDT) is an alternative treatment option for tumours of the head and neck. The principle of PDT is based on a photochemical reaction which is initiated by light activation of a photosensitizing drug causing tumour cell death. PDT damage heals mainly by regeneration rather than scarring. Due to this organpreserving principle of PDT, important structures are maintained with very good functional and cosmetic outcome. This article will review the principle of PDT and the different indications for PDT of tumours of the head and neck, focusing on small and advanced tumours of the oral cavity and the larynx as well as papillomatosis of the larynx. A critical review on the literature will be accomplished.