Melasma is a common disorder of macular hyperpigmentation which involves mostly in sun exposed areas of the face and neck. Those most affected are women. Multiple factors have been postulated to involve in the etiology and pathogenesis of melasma including pregnancy, oral contraceptives, genetics, sun exposure, cosmetics and race. We have conducted a clinical trial utilizing all trans-retinoic acid (tretinoin, Retin-A) cream 0.1% q pm and hydroquinone lotion 3% (Melanex) applied every morning in Korean women with melasma. Our study patients demonstrated all three clinical patterns common to melasma: centrofacial, malar and mandibular. Wood's light examination was performed on all patients and identified two of the four types of melasma described. Most patients showed epidermal melasma and a few manifested a mixed type. No patients exhibited solely dermal or inapparent type in melasma. With open studies of tretinoin cream and hydroquinone lotion followed by sun screen, we have found significant improvement within 5 months with a few side effects. Histopathologic examination of melasma in the pre-trial biopsies revealed increased pigmentation of the epidermis, dermis or both. In addition, significant alterations of the dermis with solar damage was noted in all melasma patients sampled. Biopsies taken after five months of treatment revealed significant decreases in epidermal pigmentation and improvement of solar damage in the dermis. We reconfirmed that a synergistic mechanism between tretinoin and hydroquinone is responsible for the improvement seen in the female Korean melasma patients from our study.