Perianal extramammary Paget's disease, Bowen's disease, and squamous cell carcinoma are three entities that are very rarely reported. Overall, it is generally accepted that wide surgical excision is adequate treatment except under certain circumstances. Consideration has to be given to invasiveness, metastatic potential, multicentricity, and tendency to recur. We describe four patients who, following unsuccessful multiple attempts at achieving microscopically clear margins with surgical excision, were treated at Roswell Park Cancer Institute with photodynamic therapy with a surface illumination method. With a minimum follow-up of 6 months (more than 1 year in three patients), there have been no recurrences to date.