Serum lipid levels in rats with hyperlipidemia induced by diet as well as by Triton were determined after oral administration of EtOAc extract of Pterocarpus marsupium heartwood and its flavonoid constituents, marsupsin [1], pterosupin [2], and liquiritigenin [3]. Administration of EtOAc extract for 14 consecutive days produced a significant reduction of serum triglyceride, total cholesterol, and LDL- and VLDL-cholesterol levels without any significant effect on the level of HDL-cholesterol. Liquiritigenin and pterosupin were able to effect a significant fall in serum cholesterol, LDL-cholesterol, and atherogenic index, pterosupin being additionally effective in lowering serum triglyceride.