We have studied 9 patients with burns (20%-75%) who had inhalation injuries and compared their actual fluid requirements with their requirements calculated from the Muir and Barclay formula. All patients were resuscitated with plasma protein fraction at a rate sufficient to keep their physiological variables within the following range: heart rate less than 120/min, central venous pressure 8-12 cm H2O, urine output greater than 30-50 ml/h, systolic blood pressure greater than 90 mm Hg and diastolic blood pressure greater than 60 mm Hg. The amount of plasma protein fraction needed was 4.38 +/- 1.26 ml/kg/% burn in the first 24 h and 2.15 +/- 0.97 ml/kg/% burn in the second 24 h. This is an increase of 75% and 110% respectively above values predicted from the formula. We suggest that the observed difference is due to a combination of the presence of an inhalation injury which increases fluid requirements by approximately 30% in the first 24 h and the use of plasma protein fraction rather than the dried plasma used in the original Muir and Barclay formula.