Chromatin remodeling is a key epigenetic mechanism of gene expression regulation controlled through the posttranscriptional modification of histones. Several enzymes, including histone deacetylases and lysine methyltransferases, add or remove functional groups at a variety of residues on histone tails. The recognition of this histone code by “reader” proteins, such as bromodomains (BRDs) and tudor domains, has a critical impact in the regulation of gene expression. The human genome encodes up to 61 different BRDs present in transcriptional co-regulators and chromatin modifying enzymes, including histone acetyl transferases and the bromodomain extra-terminal domain (BET) family. They specifically recognize e-N-acetylated lysine residues (Kac). BRDs fold into an evolutionary conserved four anti-parallel helix motif, linked by diverse loop regions of variable length (ZA and BC loops), which define the Kac binding site. [2] In most BRDs, this site features an asparagine residue mainly responsible for substrate recognition. The biological function of BRDs and their potential as therapeutic targets have been thoroughly reviewed. The large amount of crystallographic data available for most BRDs has recently shown the druggability of human BRDs, including the BET subfamily, namely BRD2, BRD3, BRD4, and BRDT, which modulate gene expression by recruiting transcriptional regulators to specific genomic locations. BRD2 and BRD4 have crucial roles in cell cycle control of mammalian cells. Along with BRD3, they are functionally linked to pathways important for cellular viability and cancer signaling and are co-regulators in obesity and inflammation. Specifically, BRD4 has been characterized as a key determinant in acute myeloid leukemia, multiple myeloma, Burkitt s lymphoma, NUT midline carcinoma, colon cancer, and inflammatory disease. Because of its continued association with Kac in mitotic chromosomes, BRD4 has been postulated to be important for the maintenance of epigenetic memory. Small molecules that inhibit BRD4 have potential as antiinflammatory, antiviral, and anticancer agents. Anticancer activity is mainly due to down-regulation of the key oncogene c-MYC. Recently, cytotoxicity in LAC cells by BRD4 inhibition has been related to suppression of the oncogenic transcription factor FOSL1 and its targets. Currently, two 1,4-diazepine derivatives, namely (+)-JQ1 and I-BET, are in preclinical development in cancer and inflammation, respectively, as potent antagonists of the BET bromodomains BRD2, BRD3, and BRD4. Recent fragment-based screenings and QSAR-based lead optimizations for the discovery of small molecules with BRD4 inhibitory activity have shed a few new relevant chemical scaffolds, including Compound 6a, an isoxazole derivative at an initial developmental stage in the clinics. During recent years, a large amount of structural knowledge about the binding features of inhibitors of BRD4 has become available by means of X-ray crystallography, providing an invaluable resource for drug discovery. The three key areas of interaction in ligand-BET bromodomain complexes are the acetyl-lysine recognition site, the WPF shelf, and the ZA channel (Figure 1c). On this basis, we performed a highthroughput virtual screening experiment using a library containing more than 7 million small molecules, aiming at the identification of novel inhibitors of the first bromodomain of BRD4 (BRD4(1); Supporting information).We selected 22