Resveratrol (1) undergoes microbial transformation when fermented with Streptomyces sp. A12 to yield 3, 5, 4′-trimethoxy-trans-stilbene (2). The structure of the compound 2 was elucidated using the modern spectroscopic techniques. This is the first report of the microbial transformation of resveratrol to compound 2 using the endophyte isolated from Polygonum cuspidatum.