Massive tissue edema after thermal injury is a well-recognized entity. Although this process is responsible for the patient's large fluid needs during resuscitation and also for local problems, such as a compartment syndrome, there have been no effective treatment modalities introduced into clinical care to control the degree of edema. A review of what is now known about the edema process is presented here, including attempted prevention and treatment modalities. The pathogenesis involves changes in most of the physical forces controlling fluid flux across the capillary and also how fluid accumulates in the interstitium. Increased capillary permeability to protein is but one of these changes. The presence of an initial profound negative interstitial pressure "sucking" fluid into the tissues and a marked increase in interstitial space compliance are equally important components. A host of mediators, especially oxidants, have been reported to cause these physical changes, and some mediator inhibitors appear to be of benefit, especially antioxidants. However, few clinical trials, aimed at decreasing edema, have been performed. With these new insights into the edema process, future prevention and treatment modalities can be developed.