We studied the effects of phytolaccosides, saponins from Phytolacca americana, on the intestinal absorption of heparin in vitro and in vivo. The absorption enhancing activity of these compounds (phytolaccosides B, $D_2$, E, F, G and I) was determined by changes in transepithelial electrical resistance (TEER) and the transport amount of heparin disaccharide, the major repeating unit of heparin, across Caco-2 cell monolayers. With the exception of phytolaccoside G, all of them decreased TEER values and increased the permeability in a dose-dependent and time-dependent manner. In vitro, phytolaccosides B,$D_2$, and E showed significant absorption enhancing activities, while effects by phytolaccoside F and I were mild. In vivo, phytolaccoside E increased the activated partial thromboplastin time (APTT) and thrombin time, indicating that phytolaccoside E modulated the transport of heparin in intestinal route. Our results suggest that a series of phytolaccosides from Phytolacca americana can be applied as pharmaceutical excipients to improve the permeability of macromolecules and hydrophilic drugs having difficulty in absorption across the intestinal epithelium.