Recent studies report that leptin may be able to modulate some functions of cells involved in non-specific immune response. We recently found that a functional leptin receptor is present on polymorphonuclear neutrophils (PMNs) and may be able to influence their oxidative capacities. We demonstrate here for the first time that leptin is also able to stimulate chemotaxis of PMNs and exerts by itself a chemoattractive effect comparable to that of well-known formyl-methionyl-leucyl-phenylalanine, and a stimulating effect on intracellular hydrogen peroxide production, without modification of phagocytosis.