Ibuprofen is an excellent anti inflammatory and analgesic drug. It possesses a chiral carbon atom in its molecule. For the two enantiomers, only the S(+)-isomer is highly active, whereas the R(-)-isomer has very low activity. S-isomer can be isolated by resolution from its racemoid and the R-isomer can be racemized under basic condition. Consequently it is highly important to determine its enantiomeric purity. In this paper, an efficient HPLC method for determination of enantiomeric purity for ibuprofen (1) through the formation of a couple of diastereomers, N-(S)-(alpha-methylbenzyl)-alpha-methyl-4-(alpha-methylpropyl)benzeneacetic amide [R,S-(2)], and (S)-(alpha-methylbenzyl)-alpha-methyl-4-(2-methyl-propyl)benzeneacetic amide [S,S-(2)], was developed using Micropak Si-5 column, petroleum ether and ethyl ether (1:1 volume) as eluate and UV detector (lambda = 300 nm). The method is convenient, rapid and accurate. The accuracy was between 99.71%-100.25%, and the average deviation was 0.064%.