The term epigenetic commonly refers to stable, environment-depending changes in genes expression that occur without altering the underlying DNA sequence. Epigenetic mechanisms are fundamental for normal development and maintenance of tissue-specifi c gene expression. Abnormalities in epigenetic processes can lead to abnormal gene function and the development of diseases. Recent evidences suggest that several diseases and behavioral disorders result from defects in gene function. Cancer, and other diseases such as autoimmune disease, asthma, type 2 diabetes, metabolic disorders, neuropsychiatric disorders, autism, display aberrant gene expression. A number of compounds targeting enzymes involved in histone acetylation, histone methylation, and DNA methylation have been developed as epigenetic drugs, with some efficacy shown in hematological malignancies and solid tumors. Recently researchers are focusing on finding new epigenetic targets for the development of new molecules for the treatment of different CNS disorders such as autism and schizophrenia targeting specific enzymes that play an important role in gene expression and function.