PIP: Case report of a 23-year-old nulliparous woman with facial melanosis manifesting itself as hyperpigmented, symmetrical areas which started during a sunny vacation is presented. Patient used oral contraceptives (Stedril-d or Ortho-Novum) for 2 years; no other drugs or cosmetics were used. Treatment with 5% hydroquinone, 0.1% triamcinolone acetonide, 0.5% tretinoin in equal parts, propyleneglycol, and ethanol 1-2 times daily for 3 months. Ortho-Novum was used during this period. No symptoms for 3 1/2 years, then recurrence after sunlight exposure. Patient used no "pill" at that time. Same treatment used with good results. Sunscreen (RV-paque) used for skin protection. Melasma consists of lightbrown to greyish sharply circumscribed, symmetrically localized spots. Histologically, increased melanin and some melanophages are found in dermal layers. Melasma is influenced by light and hormonal factors. Melanocyte-stimulating-hormone (MSH) promotes melanosome migration in dendrites coupled with skin darkening; it also activates tyrosinase. Progesterone acts on estrogen-primed melanocytes. These hormones play a role in "pill-melasma" which can occur after sunlight exposure. Melasma can result from a phototoxic or photoallergic reaction to cosmetics, tar, or other photosensitizing agents. We examined 74 patients (70 women and 4 men; ages 16-53 years) between 1973-1979. 15 patients were pregnant; 19 used the "pill" or other hormone therapy, 12 resulted from sunburn; there was no apparent cause in 26. Several depigmentation agents have been tested for treatment. Of these, hydroquinone had good results with minimal side effects. Mercaptamines were tested experimentally but not used therapeutically. 0.2% triamcinolone acetonide in cream base was satisfactory. Of 40 patients treated with either 5% hydroquinone, 0.5% tretinoin and 0.1% triamcinolone, or with corticosteroids only, 40% had good results with corticosteroids and 53% with the hydroquinone combination. Sunlight and cosmetics must be avoided and sunscreening agents used to prevent recurrence.