Photodynamic therapy (PDT), following health agency approvals throughout the world for various cancers and other diseases, is slowly being accepted as a standard treatment to be added to the medical practitioner's armamentarium. This includes palliative treatments such as for obstructive esophageal and lung cancers as well as those intended for cure, early stage lung cancer, and actinic keratoses. A particularly new and important application is for the treatment of age-related macular degeneration (AMD), where PDT (Visudyne) has made a major impact on the outcome of this disease, the major cause of blindness in those over the age of 50. In the cancer field, while not yet approved (pending), the use of PDT in treatment of high-grade dysplasia (HGD) in Barrett's esophagus may well change how this disease is currently treated (often esophagectomy). Mechanistically, the recognition of apoptosis as an important mode of cell death following PDT and the critical role of the inflammatory process and immunity has only recently been recognized. This review updates the current and future role of PDT in cancer and other diseases.