Aberrant epigenetic gene regulation by deacetylation of histone proteins has been involved in tumorigenesis. Histone deacetilase (HDAC) inhibitors ore promising anticancer agents under research and development. Romidepsin is a novel and potent HDAC inhibitor highly efficient in inhibiting HDAC activity even at nanomolar concentrations. It exhibits a considerably stronger direct inhibition in class I HDAC enzymes os compared to class II. In addition of histone deacetylation, romidepsin modulates additionol targets involved in cancer initiation and progression such os c-myc, Hsp90 ond p53. Romidepsin has shown promising anticancer effects in a wide variety of nonclinical cancer models both in vitro ond in vivo by induction of apoptosis, cell differentiation ond cell cycle arrest. Romidepsin has been recently approved by the FDA for the treatment of cutaneous T-cell lymphoma (CTCL) patients who have received at beast one prior systemic therapy. It is currently under clinical investigation for the treatment of other hematological malignances and solid tumors as monotherapy and in combination with other anticancer agents.