The Epigenase HDAC Activity/Inhibition Direct Assay Kit is a complete set of optimized buffers and reagents for measuring the activity or inhibition of total HDAC enzymes in nuclear extracts or purified HDAC isoforms (HDACs 1-11) from a broad range of species such as mammals, plants, fungi, and bacteria, and in a variety of forms including, but not limited to, cultured cells and fresh and frozen tissues. The Epigenase HDAC Activity/Inhibition Direct Assay Kit is a further refinement of its predecessor, the EpiQuik HDAC Activity/Inhibition Assay Kit, a popular assay method for HDAC activity and inhibition. This latest method retains the simplicity, rapidness, high throughput capability, and non-radioactivity featured in the previous version.