<正> The effects of polymorphonuclear leukocyte(PMN)-endothelial cell(EC) adhesion on the permeability of microvascular endothelial monolayers to fluid and albumin were investgated. It was found that: 1)the adherence of fresh PMNs to EC reduced the permeability of untreated endothelial moralayers; 2)the dherence of fresh PMN to platelet activating factor(PAF)-activated endothelial monolayers reduce(?) AF-induced high permeability