Photodynamic therapy is now a useful and practical option of the local treatment of gastrointestinal cancers. There is increasing screening and surveillance of patients at risk of oesophageal and gastric cancers. The early detection of disease is often unhelpful if an elderly or frail patient needs to be subjected to radical resectional surgery. Photodynamic therapy can eradicate and cure early mucosal disease following a single endoscopic treatment. If the disease is more advanced good local control and palliation is often possible. Overall, palliation can often be achieved using simpler methods which are highly effective and not associated with the problems of prolonged photosensitisation. It is rapidly becoming clear that the ideal indication is for the treatment of dysplastic lesions in the oesophagus associated with columnar-lined oesophagus (Barrett's oesophagus). In these circumstances a heterogeneous field change often with multifocal dysplasia or cancer can be widely eradicated. Similar areas of squamous dysplasia in the upper oesophagus can be treated. At present a major complication of stricture formation is associated with the use of some photosensitisers. The treatment of cancer at the ampulla of Vater and choriocarcinoma is also proving very effective. The treatment can be performed at endoscopy and is well tolerated and safe.