Exposure of circulating rabbit granulocytes to the chemoat-tractant N-formyl-methionyl-leucyl-phenylalanine (FMLP) in vivo results in transient granulocytopenia, hypotension, and car-diorespiratory distress. The effectiveness of vitamin E in attenuating these responses was tested. Vitamin E accelerated the rate of return of granulocytes to the peripheral circulation after FMLP-induced granulocytopeniaand mitigated the hypotension. The reversible adherence of FMLP-stimulated granulocytes to endothelium offers a plausible mechanism to explain the transient granulocytopenia.From in vitro studies it was found that FMLP-activated granulocytes from animals treated with vitamin E showed decreased adherence to cultivated aortic endothelial monolayers when compared with FMLP-activated granulocytes from control animals.