To date, no treatment for melasma has demonstrated truly satisfactory results, and so far none of these treatments have been demonstrated to prevent frequent relapses. In this review, we discuss several targets to be considered in treatment of melasma. In part I, we will discuss the findings on melanin and melanocytes in melasma. In part II, we will discuss the current understanding of the pathogenesis of increased pigmentation in melasma, i.e. melanocyte activation caused by variable stimuli.