Oral absorption of drug is very important issue especially when the drug is poorly bioavailable, given for long periods and expensive. Poorly bioavailable drugs remain sub-therapeutic because a major portion of a dose never reaches the plasma or exerts its pharmacological effect unless and until very large doses are given which may also lead to serious side effects. Any significant improvement in bioavailability will result in lowering the dose or the dose frequency of that particular drug. Several approaches have been used to maximize oral bioavailability, but with the discovery of the first bioavailability enhancer piperine in 1979, a new class of drug and a new concept was introduced in to the science. Bioenhancers or bioavailability enhancers are mostly the plant based molecules which promote the biological activity or bioavailability or the uptake of drugs in combination therapy. This review article concludes the bioavailability enhancing property of piperine.