SUMMARYWe report inhibition ofin vitrosynthesis of prostaglandins by skin in the presence of aspirin and indomethacin. In the presence of aspirin significant inhibition of enzymic synthesis of prostaglandin F2α, but not prostaglandin E2, was demonstrated. Indomethacin also caused a significant inhibition of synthesis of prostaglandin F2α, but had no effect on prostaglandin E2synthesis. Since there is increasing evidence that prostaglandins mediate some types of inflammation, the possibility arises that inhibition of prostaglandin biosynthesis explains at least part of the anti‐inflammatory activity of these dr