The inflammatory process is described with particular reference to the cardinal signs, the microcir-culatory changes and the mediators and modulators of inflammation. Mediators and modulars comprise targets for therapeutic intervention; and the arachidonic acid pathway, generating the eicosanoid group of compounds, is considered in detail. Most non-steroidal anti-inflammatory drugs (NSAIDs) of both carboxylic and enolic acid subgroups act partly and in some cases perhaps soley through inhibition of the enzyme cyclo-oxy-genase which is concerned with the generation of an important subgroup of eicosanoids, the prostaglandins. The wanted (therapeutic) and unwanted (side-effects) actions of NSAIDs are considered together with their pharmacokinetic properties. The clinical pharmacology and therapeutic uses of NSAIDs in dogs and cats are described.