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The pathogenesis and aggravation of melasma are related to sun-exposure, and the disease is usually exacerbated in summer but relieved in winter. Latest researches have shown that the direct action and indirect molecular regulation of ultraviolet radiation can enhance skin melanogenesis. Also, ultraviolet radiation can indirectly cause hyperpigmented macules via formation of free radicals. Lots of clues indicate that ultraviolet radiation and melasma are related. In addition, visible light induced-chronic photocontact allergy may be associated with the pathogenesis of melasma. This paper reviews the relationship between melasma and uvtraviolet radiation.