Ephedrae Herba (EH) is obtained by drying the stems of Ephedra sinica Stapf (family Ephedraceae). EH has been used clinically to treat colds and to reduce edema in skin. The effects of EH on melanogenesis were studied in B16 murine melanocytes. The tyrosinase activity and melanin content were measured after incubation with EH. Both reverse transcription-polymerase chain reaction and cDNA microarray analysis were used to study the mechanism of EH action. EH decreased tyrosinase activity and melanin content in a dose-dependent manner. EH decreased microphthalmia-associated transcription factor (MITF) and tyrosinase gene expression. These effects were controlled by MITF-mediated regulation of tyrosinase gene expression. EH also altered the expression of about 100 other genes. These results suggest that EH may be used clinically to treat freckles and liver spots.