This Application Note describes the experimental details and results of a Caco-2 permeability (Caco-2) assay. The approach and methodology of rapid resolution liquid chromatography and triple quadrupole mass spectrometry used in this study are described in a separate Application Note1. Experimental details and results of other typical assays performed in early ADME profiling of new hits are presented in separate publications,2,3. Improving productivity in the determination of parameters for early in vitro ADME Part 3 – Experimental details and results of Caco-2 permeability assay.