Twenty-four rats were divided into 3 groups: normal controls (8), simple burned (8), burned plus Polygonum cuspidatum (p.c.)-treated (8). Three hours after burn, 3ml of whole blood was drawn to isolate polymorphonuclear neutrophilic leucocytes (PMNs). Confluent monolayer of rat microvessel endothelial cells was grown in a parallel plate of flow chamber. PMNs were driven through the flow chamber under different wall shear stresses. Leukocyte-endothelia adhesion was observed with an Olympus inverted microscope and recorded with a colour microscopic TV set. The adhesive characteristic curve of leukocyte was significantly different between the normal and burned groups. The number of PMNs adhesive to endothelium increased obviously 3 hours after burn. Under 0.196 Pa of wall shear stress, the adhesion rate of PMNs was 81.2 + 4.1% in the burned group and 58.8 + 4.6% in the normal group. The PNMs adhesion rate was decreased to near normal in p.c.-treated group. The average survival time in the burned group was 4.1 + 1.2 hours, much lower than that in the p.c. treated group (33.2 + 15.8 hours). However, in the simple burned group, one rat survived for 24 hours and its PMNs adhesive curve was similar to that of the normal or p.c.-treated groups. The findings indicate that PMNs adhesion features increase apparently after severe burn, which is closely related to the survival rate.