This review emphasizes the benefits of ultra-high-pressure liquid chromatography (UHPLC) in the context of in-vitro drug-metabolism and pharmacokinetics (DMPK) studies. The analysis throughput afforded by UHPLC is particularly useful during the early DMPK stages, when rapid, reliable data must be generated on a large number of new chemical entities (NCEs) to select the most appropriate drug candidates. UHPLC also offers high chromatographic resolution, an important feature for the identification of unknown metabolites that are potentially generated from NCEs by a few dozen biochemical enzymes and combinations of them. Most DMPK studies require selectivity and peak-assignment certainty that is only afforded by mass spectrometry (MS) detectors. We therefore thoroughly discuss the use of UHPLC-MS and UHPLCtandem MS with regard to DMPK, highlighting the coupling of UHPLC with quadrupole-basedMS analyzers, time-of-flight MS analyzers and hybrid analyzers.