There is a great need for a procedure for the treatment of head and neck tumours, which is associated with low morbidity, and which produces results that are not functionally and/or aesthetically disabling. Photodynamic therapy (PDT) may offer such features, owing to the preferential take-up of modern photosensitizer drugs into malignant tissue, the efficient energy conversion characteristics of such drugs, and the rapidity of non-scarring, post-treatment heating. The agent metatetrahydroxy(phenylchlorin) (m-THPC, temoporfn) appears to have considerable potential as a sensitizer for PDT of head and neck tumours. An overview of studies of PDT in head and neck malignancies reveals that this modality has been used with good effects for a variety of tumour types and sites, though much remains to be learned about the importance of various parameters of PDT, including the distribution of laser energy over time. Clinical experience is described with palliative, primary, adjunctive, and multiple PDT treatment of head and neck tumours, mainly using m-THPC as the photosensitizer. In virtually all cases there was a visible response to the effects of PDT. Complications included local pain at the site of injection, and, in some cases where appropriate precautions were not taken, posttreatment skin photosensitivity. it is concluded that PDT possesses considerable potential in the palliative, primary, adjunctive and sequential treatment of patients with head and neck malignancies.