Background : Bioactive substances, viscumneoside III and homoflavoyadorinin B, were isolated from korean mistletoe. Before, the isolated compounds were performed to identify the effect on tyrosinase inhibition activity. It is generally known that the biological activity of aglycon is better than the glycone attached to sugars in natural products. Methods and Results : In this study, the glycone of mistletoe were converted into homoeriodictyol and velutin, which are aglycon, respectively, by microwave irradiation, and their tyrosinase inhibitory activity was investigated. Experimental results showed that microwave irradiation mistletoe extracts showed superior tyrosinase inhibitory activity than untreated extracts. Conclusion : These results revealed that the whitening acivity of microwave irradiation Korean mistletoe can be utilized for the skin cosmetics.