Isomers are molecules that have the same number of the same kind of atoms arranged in different ways. There are two major categories of isomers: constitutional (or structural) isomers and stereoisomers. Stereoisomers have identical sets of atoms that are configured in the same positions but are arranged differently spatially. Enantiomers are stereoisomers bearing a mirror image relationship. The pharmacological complication caused by drug racemates is that their component enantiomers usually have different pharmacodynamic effects and different pharmacokinetic properties. Enantioselective pharmacology can occur at any site in the body where a drug interacts with an endogenous chiral centre. The purpose of this presentation is to give some examples where drug chirality is pharmacologically significant to potency, uptake, distribution and elimination. The chosen examples were the anesthetic drugs, thiopentone and bupivacaine.