Voltaren, a non-steroid antiinflammatory agent (NSA) of an entirely new chemical structure, is characterized by the high degree of antiinflammatory, antipyretic and analgesic activity it displays in animal experiments. Like other NSAs, the preparation inhibits prostaglandin synthesis, and various findings indicate that the spectrum of pharmacological activity of these agents is at least partly due to this inhibitory effect. Despite this common feature, however, there are quantitative and qualitative differences between Voltaren and other NSAs.