Abstract： Objective To investigate the effects of delayed fluid resuscitation on hemodynamics and visceral perfusion in dogs with hemorrhagic shock. Methods Fourteen Beagle dogs were prepared for cannulation of carotid artery and jugular vein, and 24 hours later they were subjected to hemorrhagic shock with about 42% of total blood volume exsanguinated. Animals were divided into delayed resuscitation group ( DR group, n = 8) and immediate resuscitation group ( IR group, n = 6) . In the first 24 hours after hemorrhage, dogs in Dr group were given no fluid resuscitation, while those in IR group were immediately given resuscitation with intra-venous glucose-electrolyte solution, of which the volume was three times that of blood loss. In the second 24 hours, all animals had intra-venous fluid resuscitation. The variables of hemodynamics and visceral perfusion were determined before hemorrhage and 2, 4, 8, 24, 48 and 72 hours after hemorrhage under conscious state of dogs. Results After hemorrhage, the mean arterial pressure,cardiac output index, max of left ventricular contractility, blood flow of intestinal mucosa and urinary output greatly decreased and systemic vascular resistance obviously increased in each group compared with those before hemorrhage ( P ＜ 0.05 ) . From 4 hours after hemorrhage, the above measurements of dogs in IR group gradually resumed and reach Oh levels in 72 hours after hemorrhage except systemic vascular resistance index and intestinal blood flow. Whereas those measurements in dogs of DR group kept on worsening, and the levels of mean arterial pressure, cardiac output index, intestinal blood flow and urinary output were significantly lower than those in dogs of IR group ( P ＜ 0. 05 ) . Over 72 hours, five of eight dogs died with anuria in DR, and no animals died in IR group. Conclusion The findings indicate that delayed fluid resuscitation deteriorates hemodynamics, handicapping the restoration of visceral perfusion and increasing mortality in dogs with hemorrhagic shock.