The S3A Guideline has been successfully implemented in 1994 and, in recent years, analytical method sensitivity has improved, allowing microsampling techniques to be widely used in Toxicokinetic (TK) assessment. This Q&A document focuses on points to consider before incorporating the microsampling method in TK studies, acknowledges its benefits (and some limitations) for assessment of TKs in main study animals and its overall important contribution to the 3Rs benefits (Replacement, Reduction and efinement) by reducing or eliminating the need for TK satellite animals.