Resveratrol is naturally occurring phytoalexin compounds produced by grape berries, peanuts, pine tree, mulberry fruits and their products in response to stress such as fungal infection, heavy metal ions or UV irradiation. The objective of this study was to determine resveratrol contents in wild-type mulberry leaves (Morus alba L., M. bombycis Koidz, and M. Lhou (Ser.) Koidz) collected from Won-ju, In-je and Yang-yang regions, Gangwon province, Korea. Resveratrol contents in wild-type mulberry leaves were higher in Autumn`s than in Spring`s, and higher than 16 cultivar`s. Among the samples, ``No. 3``, collected from Won-ju region and ``No. 7`` collected from In-je showed high resveratrol contents of 539 and 491 ?g/100 g DW (dry weight; DW), respectively, through the collection time. Therefore, two mulberry trees might be promising as potent resources for mulberry breeding and functional material development.