Mefenamic acid is a non-steroidal anti-inflammatory agent with analgesic, anti-inflammatory, and antipyretic properties. It is used for the treatment of mild to moderate pain, including menstrual pain, inflammation, and fever. Clinical use of mefenamic acid has generally declined in an era where other NSAID use has flourished. While having modes of action and general toxicities similar to other NSAIDs, mefenamic acid, as a member of the fenamates, nevertheless possesses some unique in vitro effects that have the potential to distinguish this agent from others. Use of this drug remains relevant for pain syndromes and some gynecological disorders, albeit with considerable competition from other NSAIDs. New basic science has considerably improved the understanding of the biochemistry of mefenamic acid. As well as maintaining its use in traditional settings, there is a tremendous potential for expanding the application of mefenamic acid to niche roles. Mefenamic acid binds the prostaglandin synthetase receptors COX-1 and COX-2, inhibiting the action of prostaglandin synthetase. Mefenamic acid concentrations reached during therapy have produced in vivo effects. Prostaglandins sensitize afferent nerves and potentiate the action of bradykinin in inducing pain in animal models. Prostaglandins are mediators of inflammation. Because mefenamic acid is an inhibitor of prostaglandin synthesis, its mode of action may be due to a decrease of prostaglandins in peripheral tissues.