Leukocytes have been shown to play an important role in the development of isolated organ injury after experimental ischemia and reperfusion. To examine the role of leukocytes in generalized ischemia-reperfusion injury we used the MAb 60.3 (directed to the human leukocyte adherence glycoprotein, CD18) to block leukocyte adherence functions in a rabbit model of hemorrhagic shock and resuscitation. In control animals subjected to 1 h of shock (mean blood pressure 45 torr and mean cardiac output 30% of baseline) followed by resuscitation, only 29% survived 5 d. All had gross and histologic evidence of injury to lungs, liver, and gastrointestinal mucosa. In contrast, 100% of the MAb 60.3-treated animals survived 5 d (P less than 0.01) and organ injury was absent or markedly attenuated. The control animals also had a persistent acidosis, lost more weight, and had evidence of continued gastrointestinal bleeding in contrast to MAb 60.3-treated animals. We conclude that increased leukocyte adhesiveness plays an important role in the development of multiple organ injury and death after generalized ischemia-reperfusion and that this injury may be significantly reduced by blocking leukocyte adherence functions with the MAb 60.3.