In 1980 patients with burns greater than 10% of total body surface area (TBSA) received a mean of 8 units of blood (range, 0-42 units) during hospitalization in our burn center. Concern about the risks of blood transfusion caused us to reassess our transfusion practices and to question the need to maintain hematocrits above 30%. We compared the quantity of blood given to burn patients at Harborview Medical Center in 1980 with that given in 1990. Available records were reviewed from all patients with greater than 10% TBSA burns who required at least one operation (1980; n = 41; 1990: n = 38). There were no differences between groups for patients' ages, timing of first excision, or length of hospital stay. There were no differences in extent of burn excision per operation, but surgical times were significantly shorter in 1990 than in 1980. In 1980, 1.2 +/- 1.2 mL of blood was transfused per square centimeter surface area excised, compared with 0.23 +/- 0.49 mL in 1990 (p < 0.0001). In 1980, 133 +/- 153 mL blood was transfused per patient per percent burn during the acute hospitalization, compared with 20 +/- 34 mL in 1990 (p < 0.0001). There have been no instances of myocardial infarction or congestive heart failure related to the maintenance of lower hematocrits. We now permit hematocrits to fall to 15%-20% in healthy patients who need limited operations. In healthy patients with more extensive burns we accept hematocrits of 25%, and only critically ill patients and those with pre-existing cardiovascular disease are transfused to hematocrits of 30% or higher.