Hibiscus syriacus L. (Malvaceae) is widely distributed over Korean, China, India and Siberia. The dried flower of Hibiscus syriacus is used as a folk medicine for curing of hematochezia, dysentery, obstruction due to wind-phlegm, regurgitation, and vomiting of food, and the dried root bark is used antipyretic, anthelmintic and antifungal agents. From a chloroform extract of root bark of this plant, compound I, II, and III were isolated and the structures were elucidated by various spectroscopic analyses. These compounds were identified as syringaresinol. E-N-feruloyltyramine, and Z-N-feruloyltyramine, respectively and were isolated from this plant for the first time. Compound II and III exhibited lipid peroxidation inhibitory activities with $IC_{50}$ of 15.5 and 28.6 ${mu}g/ml$, respectively.