The aim of this study was to investigate whether heparan sulfate, as an adjunct to resuscitation following hemorrhagic shock: (1) improves gut absorptive capacity, and if so, (2) whether the mechanism involved is alteration of whole blood viscosity (WBV). Rats were anesthetized, a laparotomy performed, and blood vessels cannulated. The conscious animals then underwent fixed pressure (40 mm Hg) hemorrhage, followed by resuscitation with lactated Ringer’s solution. One group received 7 mg/kg heparan sulfate, and another received saline, during resuscitation. At 2 hours and 4 hours after the end of hemorrhage, the oral D-xylose absorption test was performed. Viscosity determinations were made in another set of rats since lactated Ringer’s solution replacement during the D-xylose test may affect hematocrit and hence WBV. These rats were subjected to hemorrhage and resuscitation as above, along with additional sham hemorrhage and acute hemodilution control groups. The WBV was determined at corresponding times to the D-xylose test. Results show that xylose absorption is depressed after hemorrhage and resuscitation, and heparan sulfate restored it to normal. The WBV was reduced by heparan sulfate. Thus heparan sulfate, as an adjunct to resuscitation of hemorrhagic shock, restores gut absorptive capacity to normal, possibly by reducing WBV. © 1993 by Williams and Wilkins.