Estimates of the height of patients in the intensive care unit are required to adhere to clinical guidelines for drug dosages, ventilatory support, and nutrition. The gold standard of standing height cannot be used because these patients are often unconscious and recumbent. The ability of physiotherapists or dietitians to measure height in unconscious, recumbent patients has not been evaluated. To compare the accuracy of physicians, physiotherapists, and dietitians in estimating the height of recumbent critical care patients by using existing practice methods. A total of 35 patients were recruited from the cardiothoracic preadmission clinic, where standing height is routinely measured by a physiotherapist. After surgery, in the intensive care unit, 1 physician, 2 physiotherapists, and 2 dietitians measured each recumbent patient's height. Three methods were used: observation, whole-body measurement, and height estimated by using length of the forearm and the British Association for Parenteral and Enteral Nutrition normative chart. Difference from standing height was measured from zero and was compared across professions and methods, with zero indicating no difference. Overall, 17 physicians, 4 dietitians, and 9 physiotherapists consented to measure patients. After adjustments for method, measurements by physiotherapists did not differ significantly from the gold standard (P = .59), whereas those of physicians (P = .02) and dietitians (P < .001) did. Physiotherapists' measurements of supine height of recumbent critical care patients, obtained by using a nonrigid measuring tape, are more accurate than measurements obtained by physicians and dietitians.