The influence of total brain gangliosides on acute inflammation was investigated using the rat hind paw edema test. Total gangliosides (10 micrograms/paw) inhibited the edema produced by the injection of bee venom phospholipase A2 (5 micrograms/paw) when the lipids were co-injected or injected 15 min before the phospholipase A2. Sulphatide (10 micrograms/paw) did not inhibit the edema but potentiated it. Gangliosides (40 micrograms/paw) inhibited the edema induced by carrageenin 1% when they were injected 1 h before the agent. However, gangliosides (up to 200 micrograms/paw) failed to inhibit the dextran-induced edema. The edema test was also used to investigate the effect of gangliosides on the production of mediators of inflammation by peritoneal adherent macrophages. Gangliosides inhibited the production of mediators of inflammation only when they were incubated with these cells before the stimulation with phospholipase A2 or carrageenin. Gangliosides did not inhibit the production of mediators of inflammation when arachidonic acid was added to the cells. These results suggest that the anti-inflammatory effect observed with gangliosides is mediated by inhibition at or before endogenous phospholipase activity.