Erosive pustular dermatosis of the scalp is a rare condition that tends to occur mainly in elderly patients. Clinically it is characterized by the presence of pustules, chronic crusted erosions with progressive scarring alopecia, and skin atrophy. Although etiology remains unclear, it seems to be triggered by local trauma such as surgical procedures, skin graft, ultraviolet light exposure, cryotherapy, craniotomy, or radiotherapy. To our knowledge, erosive pustular dermatosis of the scalp after photodynamic therapy has been seldom reported. We described a 81-year-old woman presenting with erosive pustular dermatosis of the scalp after photodynamic therapy for actinic keratosis.