In this study, 18 copies of PLAVIX tablets containing clopidogrel hydrogensulfate were compared to the innovator drug product for uniformity of mass, impurity profile, content, dissolution properties and stability. In order to be able to separate the R-enantiomer of clopidogrel, an enantiospecific liquid chromatographic method was used to determine the impurities and to perform the assay. The paddle method was used for dissolution testing. Most of the copies were not similar compared to the original drug product: their amount of impurities was higher, the content of clopidogrel lower, the dissolution profiles different and after 3 months under stress conditions in the original packaging, the results for the samples and the reference were significantly different in most of the cases.