The chaga mushroom, Inonotus obliquus has long been recognized as a remedy for cancer, gastritis, ulcers, and tuberculosis of the bones since the 16th century.Herein we reported the identification of two homogenous lignin-carbohydrate complexes, designated as IOW-S-1 and IOW-S-2 with antiproliferative activities from the hot-water extract of Inonotus obliquus.