Inflammation is the response of living tissues to injury. It involves a complex array of enzyme activation, mediator release, extravasation of fluid, cell migration, and tissue breakdown and repair. This chapter will concentrate on the inflammatory aspects of prostaglandins, and in particular prostaglandin E2 (PGE2), which is derived from arachidonic acid via the action of the enzyme cyclooxygenase (COX). PGE2 is the predominant eicosanoid detected in inflammatory conditions in humans ranging from experimental acute edema and sunburn to chronic arthritis and certain neurological disorders. Since inflammation is one of those few conditions in which PGE2 is a major product of COX, it is entirely conceivable that the inflammatory process itself directs the enzymatic pathway toward generation of this specific product.