Acetylation of histones such histone H4 has been involved in the regulation of chromatin structure and the recruitment of transcription factors to gene promoters. HATs (histone acetyltransferases) and HDACs (histone deacetylases) play a critical role in controlling histone H4 actylation. Reversible acetylation of nucleosomal histone H4 is believed to correlate with potential transcriptional activity of eukaryotic chromatin domains. The reversible lysine acetylation of histone H4 may play a vital role in the regulation of many cellular processes including chromatin dynamics and transcription, gene silencing, cell cycle progression, apoptosis, differentiation, DNA replication and repair, nuclear import and neuronal repression. The kit enables the user to fluorometrically detect and quantify if histone H4 is acetylated. The kit is ready-to-use and provides all the essential components needed to carry out a successful assay experiment. The kit is suitable for specifically measuring total histone H4 acetylation using a variety of mammalian cells including fresh and frozen tissues, and cultured adherent and suspension cells.