The effects of two long-acting anti-inflammatory agents on behavioral changes and cerebral vasospasm were evaluated in a canine model of chronic subarachnoid hemorrhage (SAH). The agent with the longest half-life, sudoxicam, clearly reduced both the incidence and the magnitude of the vasopasm, and prevented the usual behavior changes caused by the stimulated SAH. The results obtained with the other agent, naproxen, suggested that it was better than the administration of saline. These agents were studied because of reports indicating that prostaglandins and thromboxane may play a role in the pathogenesis of the effects of SAH and because of nonsteroid anti-inflammatory agents exert pharmacological effects by reducing an excessive synthesis of these lipids. The findings suggest that some of these agents may afford an alternative treatment for the deterious consequences of SAH.