Background : Skin color is determined by many factors including melanin and nonmelanin pigments like hemoglobin and extraneous chemicals. Various factors such as race, sex, and age have been reported to have an influence on skin color. Methods : Measurement of malanin index (M-index) was made by reflectance spectropho-tometer at three different sites including forehead, abdomen and forearm in total 800 healthy subjects consisting of 100 males and 100 females of neonates (three days after birth) and children (male:8.08±0.84, female:8.03±0.80, total :8.06±0.82 years of age), ado-lescence (mate:13.89± 0.76, female:13.96±0.79, total:13.93±0.78 years of age), and adults(male:24.26±0.82, female:24.40±0.89, total:24.33±0.86 years of age). We also investigated the change of M-index by each skin phototype of college students determined by Fitzpatrick classification. Results : From the birth to the puberty, sex difference of melanin index was generally not not-ed, but adult females showed lower levels of melanin index in all sites measured. M-index in-creased from birth to adolescence, and decreased after adulthood. Forehead showed highest melanin index compared with other sites. Increase of M-index was noted as skin phototype goes from Ⅲ to Ⅴ. Conclusions : Factors including sex, age, body sites and skin phototype have a significant in-fluence on the changes of skin color in humans.(Ann Dermatol 14(2) 71-76, 2002)