Massive wound edema after a burn may impair healing and help to convert partial to full-thickness injury. Cold treatment (usually by immersion) has been reported to decrease wound edema and is useful in first-aid treatment of burns. Reliable quantitative data have been lacking and frequently a superficial burn has been studied. Since cold by decreasing peripheral blood flow could actually be harmful to a deep burn, especially if applied late, we measured the effect of cold immediately and 2 minutes postburn on edema formation and resorption in a deep second-degree burn in sheep hindlimbs. We used Dichromatic Absorptiometry, a noninvasive, reliable method for measuring tissue fluid, to quantitate edema. Immediate application of cold by immersion in 15 degrees C saline for 30 minutes reduced the edema of a deep second-degree burn and did not impair resorption rate compared with control limbs, fluid content returning to baseline after 1 week. Cold treatment beginning 2 minutes after the burn did not decrease edema formation and did impair resorption. Fifteen per cent of the edema fluid was still present 1 week postburn, suggesting further injury to the burn wound vasculature with use of cold immersion 2 minutes postburn.