Polygonum cognatum Meissn., which is also known as “madımak, solucanotu” has been used in the Turkish folk medicine for the treatment of various diseases and has also been consumed in the dishes and salads by local people. It has even been the subject of a folk song, sung among the people in Sivas. In this study, it was aimed to examine the resveratrol and phenolic compounds that are valuable for health industry, in leaf and root extracts obtained from P. cognatum, which is widely distrubuted in Sivas. While resveratrol was investigated by using HPLC- PDA, the phenolic compounds were determined by using LC-HRMS. Results of analyses showed that resveratrol could not be detected in both leaf and root extracts, but both root and leaf extracts were quite rich in following phenolic compounds. While chlorogenic acid, hyperoside, rutin, and fumaric acid were the most abundant phenolic compounds detected from the leaf extract, the (+)-catechin, fumaric acid, chlorogenic acid and p-coumaric acid were the most abundant phenolic compounds in the root extract. As a conclusion, P. cognatum with its rich phenolic compounds content of the root and leaf parts are good candidates in terms of using in dietary supplements, health care and cosmetic products.