Histone deacetylases (HDACs) and histone acetyltransferases (HATs) are enzymes that catalyze the deacetylation and acetylation of lysine residues located in the NH2 terminal tails of histones and non-histone proteins. Perturbation of this balance is often observed in human cancers and inhibition of HDACs has emerged as a novel therapeutic strategy against cancer. To date, more that 30 groups, academic and industrial, are involved in research related to these target enzymes. Over the past year, dozens of research papers and patent applications describing new HDAC inhibitors belonging to different structural classes have been disclosed. The present review highlights the latest developments in design and synthesis of HDAC inhibitors - potential anti-cancer drugs.