The role of photodynamic therapy (PDT) in the treatment of primary non-melanoma skin cancer is examined. Prolonged systemic skin photosensitivity limits the usefulness of PDT using conventional photosensitisers such as Photofrin-II. However in exceptional circumstances, such as multiple or widespread basal cell carcinomas, this therapy provides a useful and seemingly effective alternative mode of treatment. For Bowen's disease, PDT using topical 5-aminolaevulinic acid (ALA) yields high response rates and excellent cosmetic results. For large lesions and those in anatomically difficult sites or in poorly vascularised skin, ALA-based PDT can be considered the treatment of choice. Recent pharmacological and technological developments may further enhance the efficacy and convenience of photodynamic therapy, and make it more generally available in non-specialist centres.