BACKGROUND Autoimmune progesterone dermatitis (AIPD) is caused by an immune reaction to endogenous progesterone following exposure to exogenous progesterone, especially in oral contraceptives and intrauterine devices. Skin eruption develops cyclically during the luteal phase of the menstrual cycle when progesterone levels are elevated. The resultant clinical symptoms are frequently confused with other forms of dermatosis. We describe a young woman presenting AIPD. METHODS A 23-year-old woman had a history of a chronic pruritic papular-vesicular eruption on the trunk, present since the onset of puberty and unsuccessfully treated with antihistamines and topical steroids. Skin lesions normally began a few days before menstruation and resolved a few days afterwards. Intradermal testing using progesterone was positive, thereby confirming the diagnosis. The patient's skin lesions improved under oral contraceptives designed to inhibit ovulation and there was no relapse during subsequent menstrual cycles. CONCLUSIONS AIPD is a rare autoimmune disorder. The diagnostic criteria of AIPD include recurrent cyclical worsening of skin lesions and symptomatic improvement after inhibition of progesterone secretion by suppression of ovulation. The pathogenesis is unclear. Positive response to various tests with progesterone suggests involvement of various mechanisms such as antibodies and/or cell-mediated immune reactions. CONCLUSIONS AIPD is a rare disease that can seriously affect patients' quality of life and which may even be life-threatening in certain cases.