We examined the effect of quinacrine, an anti-malarial drug which inhibits phospholipase A2, on phorbol myristate acetate (PMA) stimulated alveolar macrophage oxygen radical secretion. This drug suppressed 30% of radicals release, which was 70% of the amount inhibited by superoxide dismutase, a specific inhibitor of oxygen radicals. In addition, this reduction was at the same magnitude as dexamethasone. This and previous results on other inflammatory cells support the assumption that quinacrine may have a beneficial effect on bronchial asthma.