Pentoxifylline (Trental) is a well-known vasoactive drug with proven clinical efficacy in various circulatory disorders. It improves the microcirculation due to its rheologic effects on red blood cells, platelets, and plasmatic components, resulting in a decrease of whole blood viscosity. Surprisingly, it has been found that pentoxifylline will also be of great benefit in different models of animal sepsis, including both gram positive and gram negative bacteria. In these experiments, survival rates are significantly increased in the pentoxifylline group when compared with the controls, which is paralleled by a decrease in germ counts. By different experimental approaches it could be shown that this drug interferes with pathologic granulocyte-endothelium interactions which are closely related to septic symptoms, both downregulating intravasal granulocyte hyperreactivity as well as stimulating antiaggregatory activity of the vessel endothelium. Through this way, beneficial effects of pentoxifylline may be expected in various diseases related to infection, sepsis, and shock which, however, have still to be proven in detailed clinical studies.