Following the discovery of inducible COX-2 in arthritic joint fluid and immunocompetent cells a revolution in the field of antiinflammatory treatment was expected. The detection of a constitutive COX-2 in the kidney, in stomach and central nervous system destroyed this hypotheses. Further experiments in animal models were done to elucidate the role of the constitutive COX-2 in different physiological and pathophysiological states. In central nervous system was shown that the constitutive COX-2 is the predominant isoform of cyclooxygenases in brain and spinal cord and is highly regulated by different mediators. After experimental induction of peripheral inflammation a significant induction of COX-2 gene, protein expression and synthesis of prostaglandins in the spinal cord was detected. It was concluded that COX-2 is strongly involved in pain mediation processing in the spinal cord. The detection of COX-2 in the brain endothelial cells and its role in fever led to new insights of development and time course of temperature elevation. Probably, the use of selective COX-2 inhibitors decreases fever more effective than “classical” antipyretics. Furthermore, newer results show a role of COX-2 in differentiation and maturation processes in brain. These findings implicate new ways for the treatment of Alzheimers disease and other degenerative brain disorders. Clinical and experimental results with selective COX-2 inhibitors show a better safety profile than non-selective COX inhibitors. The clinical use after drug registration will be decide on the further role of this new class of drugs in analgesic/antiinflammatory therapy and on new fields of clinical use.