Drug development and therapy design are typical areas where relatively large databases are often encountered. The processes of absorption, distribution, metabolism, and elimination are very complex and patterns are hard to find. Therefore, methodology, called data mining, is often needed to extract every possible information from the data. Detailed analysis of the databases can shorten drug development time, reduce costs, and provide more efficient dosage regimens. The aim of this article is to present and discuss problems of data analysis in pharmacokinetic studies which are illustrated with the example of a bioequivalence study database analysis. Suitable graphical representation of data is a simple tool in data mining, however, combined with modelling and simulation can become very effective.