The purpose of this study was to determine the contribution of neutrophils and tissue xanthine oxidase to the skeletal muscle microvascular dysfunction in an ex vivo model of acute compartment syndrome. Adult dogs were rendered neutropenic or depleted of tissue xanthine oxidase before gracilis muscle isolation. Compared with continuously perfused, nonischemic muscles, acute, experimental compartment syndrome resulted in a dramatic increase in microvascular permeability, muscle neutrophil content, and muscle vascular resistance. Neutropenia prevented, whereas xanthine oxidase depletion had no effect on, the microvascular dysfunction and muscle neutrophil infiltration elicited by experimental compartment syndrome. These results suggest that neutrophils contribute to the microvascular dysfunction and blood flow distribution abnormalities elicited by acute, experimental compartment syndrome.