Hypertonic saline solutions (HSS) have several characteristics that may improve the survival of patients during the initial treatment of certain types of shock. The use of isotonic crystalloids for resuscitation has several limitations: large infusion volumes are needed to increase the intravascular space; these large volumes cannot be given rapidly; and the fluid rapidly redistributes throughout the extravascular space. HSS are administered as a small-volume bolus over a few minutes and, by mobilizing extravascular water to the intravascular space, result in an immediate restoration of intravascular volume that can last several hours. Additional properties of HSS include positive effects on cardiac function, the microvasculature, and the immune system that not only justify their use in shock resuscitation but also suggest the opportunity for other applications.