Photodynamic therapy (PDT), which employs a combination of a tumor-localizing photosensitizer and visible light, has been used in the treatment of extramammary Paget's disease (EMPD). Two patients with EMPD were treated with PDT using 5-aminolevulinic acid (ALA). Histologically, in both cases, Paget's cells were present within the epidermis. Case 1 was a 92-year-old male who underwent total extirpation for treatment of EMPD. Two topical ALA-PDT treatments were applied to parts of the lesions at a total dose of 200J/cm2. Case 2 was a 73-year-old female, whose lesions in the right labia majora were treated with 3 topical ALA-PDT sessions at a total dose of 300 J/cm2. Clinical findings after the irradiation showed improvement in both patients, and elimination of tumor cells in the epidermis was confirmed histologically. Case 1 had no recurrence in the irradiation field at three months after PDT. Case 2 had a recurrence only in the periphery parts of the lesions at two months after PDT, but the periphery lesions remitted with two more PDT treatments. Topical ALA-PDT is an effective treatment for EMPD with tumor cells within the epidermis. It is noninvasive and achieves a cosmetically excellent outcome, especially in elderly patients and those in poor general condition.