AIM　To investigate the effects of ginkgolide B on arachidonic acid (AA) metabolizing enzymes and the level of intracellular calcium in rat polymorphonuclear leukocytes. METHODS　Intracellular free calcium was quantitated by Fura-2 fluoresence technique. Phospholipase A2 (PLA2) activity was determined by incorporating 3H-arachidonic acid in leukocytes. 5-Lipoxygenase (5-LO) activity was evaluated by RP-HPLC. RESULTS　In comparison with control, ginkgolide B at final concentration of 0.1-10 μmol*L-1 inhibited A23187 induced AA release by 10.9%-22.2%; at final concentration of 0.1-50 μmol*L-1, ginkgolide B inhibited LTB4 and 5-HETE synthesis stimulated by PAF by 29.4%-88.8% and 26.2%-89.3% respectively. At the final concentration of 0.1-100 μmol*L-1, ginkgolide B decreased the rise of intracelluar calcium level induced by pletelet activating factor (PAF) and N-formyl-methionine-leucine-phenglalanine (fMLP) by 13.9%-51.4% and 2.2%-36.6%, respectively. CONCLUSION　Ginkgolide B was found to significantly inhibit PLA2 and 5-LO activities, as well as the increase of the intracellular calcium induced by PAF.