Pedunculagin is an ellagitannin purified from Alnus hirsuta var. microphylla. Betulaceae. The effects of pedunculagin on immune system have been characterized to induce enhancement of NK (natural killer) cell cytotoxicities against tumor cells. Here, we report the evaluation of the effects of pedunculagin on the growth of murine Bl6-F10 melanoma in vivo. After the intradermal inoculation of Bl6-F10 melanoma, Bl6-F10 tumors grew progressively in immunocompetent syngenic C57BL/6 mice. The mice treated with pedunculagin(10 mg/kg, every 48 hrs) resulted in a significant improvement in survival. Inhibitory effects of pedunculagin on lung metastasis in C57BL/6 mice were also detected. Summarizing treatment with pedunculagin has a significant antitumor effect upon Bl6-F10 murine melanoma.