Histone deacetylases (HDACs) represent a large family of enzymes identified as key regulators of nucleosomal histone acetylation, a major event that controls eukaryotic gene transcription and are classified into three groups. They are believed to be involved in important biological activities, such as cell differentiation, proliferation, apoptosis, and senescence. In BioVision’s HDAC-8 Inhibitor screening Kit, HDAC-8 deacetylates the substrate (R-H-K(Ac)-K(Ac)-AFC) followed by an enzymatic cleavage to release the quenched fluorescent group (AFC), which can be detected at Em/Ex = 380/500 nm. In the presence of an HDAC-8 inhibitor, the deacetylation will be impeded which prevents the cleavage of the substrate to release AFC. The kit provides a rapid, simple, sensitive, and reliable test, which is also suitable for high throughput screening of HDAC-8 inhibitors. Trichostatin A is included as a control inhibitor to compare the efficacy of the test inhibitors.