The present experiment used modified Evans blue fluorimetry to determine changes in pulmonary vascular permeability using a delayed resuscitation model of burn shock in rats. The results showed that pulmonary vascular permeability in the immediate resuscitation (IR) group regressed to normal 12-24 h following the burn whereas it regressed slowly in the delayed resuscitation (DR) group. The study showed that Evans blue fluorimetry is a reliable and sensitive method for determining pulmonary vascular permeability, and dimethyl formamide is a preferable extracting solution which provides a quick and convenient means for scientific research.