Hypothesizing that reduced blood flow to various levels in thermally damaged dermis is related to the depth of burn, we studied 59 burns in 41 patients, with an age range of 18 months to 67 years, with improved laser Doppler blood flow technology to determine burn depth on admission. Two hundred and sixty-eight laser Doppler measurements were made in 59 burn wounds in 41 patients. Of the 129 burn wounds with laser Doppler readings of less than 1.4 on admission, 127 were classified ultimately through clinical observation as either deep second- or third-degree burns and required excision and closure. Therefore predictive value of a positive result (i.e., laser Doppler value less than 1.4) on admission was 98.4% using laser Doppler measurements. Clinical estimation did not correlate as well with the depth of injury.