A number of currently available therapeutic agents for the management of idiopathic inflammatory bowel disease were studied with respect to their influence on blood flow and oxygen extraction in the dog colon. Some commercially available corticosteroid enemas including Cortenema and its vehicle and sulfasalazine and its split products were delivered intraluminally while arterial pressure, blood flow and oxygen extraction in autoperfused segments of the colon were continuously monitored. Of the agents studied, only Cortenema and its vehicle exerted any appreciable effect on colonic blood flow, producing a sustained 50% increase; this increase in blood flow was confined to the mucosa-submucosal layer. Of the constituents of Cortenema, methylparaben was responsible for 72% of the hyperemia whereas the remainder was due to carboxypolymethylene. The corticosteroid itself had no effect. Oxygen uptake by the colon was reduced by approximately 10% with Cortenema, this reduction being due entirely to polysorbate 80. In vitro analysis of the oxygen uptake effect indicates that the enema exerts a direct metabolic action.