Incurred sample reanalysis (ISR) is accepted as both a fundamental concept and an integral part in the conduct of pharmacokinetic, bioequivalence and preclinical safety studies. Reproducibility demonstrated by ISR reinforces confidence that the method is valid and the results dependable. In this article, the history of the uptake of ISR is discussed and the current practices described. The industry is given credit for its awareness of the importance of, and implementation of, ISR practices in bioanalytical laboratories. Finally, in the context of the recent publication of guidelines for ISR by the EMA, implications for globalization and harmonization of regulations pertaining to ISR are described.