Facial melanosis may be distinguished on the basis of etiology, associated morphologic changes, and distribution. Factors contributing to the development of such pigmentation are contact dermatitis, sun exposure, systemic hormonal alterations, and toxic substances. Among these facial disorders may be listed; melasma, postinflammatory hyperpigmentation, Riehl's melanosis, and mercurial pigmentation. In order to compare facial melanosis, Ewha Womans University Hospital studied 1977 patients from July 1,1980 to June 30, 1981. The results were as follows: 1. The favorite site of melasma was cheek, malar prominences, and forehead in that order. Postinflammatiry hyperpigmentation occurred on the forehead, malar prominences, and the cheek in that order. Riehl's melano-sis developed on the face and mercurial pigmentation was on the cheek, malar prominences, and forehead. 2. The color of melasma was mostly brown, dark brown and subsequently light brown in that order. Postinflammatory hyperpigmentation was mostly dark brown, brown and subsequently light brown in that order. The color of Riehl's melanosis and mercurial pigmentation was dark brown. 3. In spring and summer seasons, melasma, postinflammatory hyperpigmentation and Riehl's melanosis were exacerbated by sunlight, but mercurial pigmentation was not affected by sunlight. 4. In all 19 cases (melasma 12 cases, postinflammatory hyperpigmentation 4 cases, Riehl's melanosis 2 cases, mercurial pigmentation 1 case) the C.B.C., urinalysis and liver function tests, were within normal limits. 5. In 19 cases biopsy specimens revealed an increase of melanin pigment and chronic inflammatory cell infiltration. In one case, the findings were similar to those of a tattoo biopsy and 2 cases showed free zone beneath the papillary body. Patients with facial melanosis, characteristically have a similar history, clinical and laboratory findings, and disease course.