Tilorone suppressed inflammation induced by immune (direct passive Arthus reaction) as well as by non-immune agents (carrageenam-induced paw edema and abscess formation), if the compound is given 24 hr prior to the proinflammatory agonists. The non-immune anti-inflammatory effect is independent of the adrenals. A surprising findings was that total serum hemolytic complement is markedly elevated 24 hr after a single dose of tilorone.