Autoimmune progesterone dermatitis is a rare disorder that presents as a cyclical cutaneous eruption during the luteal phase of the menstrual cycle. It typically occurs in women due to an autoimmune phenomenon to endogenous progesterone production. We describe a 34-year-old woman with an erythematous round plaque with blistering, which recurred a few days before her menstrual cycle, at the identical site on the left arm. The diagnosis of autoimmune progesterone dermatitis is made with i.d. skin testing on the affected lesion with progesterone. After the beginning of oral prednisolone (40 mg daily) therapy during menstruation, although slight recurrence appeared, the severity was significantly improved.