Inflammatory processes are the response of the organism to potentially harmful stimuli, such as infection, trauma, and immunological events. The inflammatory reaction is characterized by the release of a variety of inflammatory mediators and modulators that alter microvascular functions and govern leukocyte recruitment and extravasation of plasma components. Activation of phospholipase A2 (PLA2) induces the mobilization of fatty acids, particularly arachidonic acid (AA), from the membrane phospholipid pool. AA is the principal precursor of the eicosanoid family, which comprises the prostaglandins, prostacyclin, and thromboxanes formed along the cyclooxygenase pathway, and leukotrienes, lipoxins, and a number of hydroxy acids derived from AA via the lipoxygenase pathway. The eicosanoids are remarkably prevalent and contribute to a broad spectrum of physiological and pathological processes, such as vascular and nonvascular smooth muscle tone, thrombosis, parturition, gastric secretion, inflammation, and wound healing. Several classes of substances, most notably the nonsteroidal anti-inflammatory drugs (NSAIDs), owe their therapeutic potential to inhibition of eicosanoid biosynthesis. PLA2 also generates a set of modified phospholipids, currently referred to as platelet-activating factor (PAF), thought to be involved in inflammatory processes.