Pharmacological suppression of cyclooxygenase (COX)-1 and -2-mediated prostanoid biosynthesis by non steroidal anti-inflammatory drugs (NSAIDs) is used in the therapy of inflammation, fever, and pain. However, long-term application of these drugs is associated with severe side effects, mainly gastrointestinal injury and renal irritations, apparently due to impaired biosynthesis of physiologically relevant prostanoids. Although COX-2 selective drugs (coxibs) show reduced gastrointestinal complications, recent clinical trials indicated a significantly increased cardiovascular risk. In order to minimize these side-effects, selective suppression of microsomal prostaglandin E(2) synthase (mPGES)-1 derived prostaglandin (PG)E(2) formation has been considered as alternative to general inhibition of prostanoid biosynthesis. mPGES-1 is functionally coupled to COX-2 being responsible for excessive PGE(2) generation connected to pathologies and current knowledge suggests key roles of mPGES-1 in inflammation, pain, fever, atherosclerosis, and tumorigenesis. However, mPGES-1 as promising therapeutic target was questioned because blockade of mPGES-1 allows redirection of the substrate PGH(2) to other PG synthases, and the consequences are still elusive. This review summarizes current knowledge about synthetic and natural mPGES-1 inhibitors focusing on structural and mechanistic investigations. Further, the therapeutic efficiency and safety is critically discussed on the basis of cellular and animal studies in which mPGES-1 activity was pharmacologically or genetically (knockout, knockdown) modulated.