Histone acetyltransferase(HAT) and histone deacetylase(HDAC) are enzymes having opposite function.They modulate the degree of acetylation of histone and regulate gene expression by addition or removal,respectively,of acetyl groups to e-amino groups in N-terminal tails of histone and have affinity with the occurrence of cancers.Recent researches found that histone deacetylase inhibitors can inhibit proliferation,induce differentiation and/or apoptosis of tumer cells by up-regulating histone acetylation and the expression of transcription factors,such as p21,p53.According these,many HDAC inhibitors have been found or synthesized as new potent effective anticancer drugs.The research progress of HDAC inhibitors systema-(tically) are reviewed.