The aim of this study was to evaluate the efficacy of photodynamic therapy in the management of residual neoplasms of the perianal skin.This is a retrospective review. Five patients with pathologic confirmation of residual perianal neoplasms were treated with photodynamic therapy. There were three females. The mean age was 52 (range, 33-79) years. Pathology consisted of Bowen's disease in two patients, squamous-cell carcinoma in two patients, and extramammary Paget's disease in one patient. Four patients received one photodynamic therapy treatment and one patient received two treatments three months apart.Treatment was followed by immediate perianal erythema, subsequent blister formation in 36 to 48 hours, and sloughing of the treated area in 72 hours. With a mean follow-up of 5.2 (range, 1-8) years, there were two recurrences. One recurrence was in a patient four years after treatment for Paget's disease, and the other was in a patient nine months after treatment for Bowen's disease. The latter was managed successfully with wide local excision. Treatment-related toxicities included significant perianal pain in four patients, controlled with analgesia management.Photodynamic therapy can successfully be used after wide local excision for residual neoplasms of the perianal skin. Treatment can be rendered with acceptable morbidity.