Drugs which have a center of asymmetry are often administered as an equal mixture of the two possible enantiomeric forms i.e. a racemate. However, there are frequently large pharmacodynamic and pharmacokinetic differences between enantiomers. Consequently, it is possible that while one enantiomer mediates the antiinflammatory or antirheumatic action, the other enantiomer, although adding little to the efficacy of the drug, may contribute to its adverse effects. Asymmetric drugs may also serve as sensitive pharmacological probes of the mechanisms underlying the action of drugs and the inflammatory processes which they modulate. These concepts are the focus for this review.