An orally bioavailable, small-molecule histone deacetylase (HDAC) inhibitor with potential antineoplastic activity. HDAC inhibitor SB939 inhibits HDACs, which may result in the accumulation of highly acetylated histones, followed by the induction of chromatin remodeling; the selective transcription of tumour suppressor genes; the tumour suppressor protein-mediated inhibition of tumour cell division; and, finally, the induction of tumour cell apoptosis. This agent may possess improved metabolic, pharmacokinetic and pharmacological properties compared to other HDAC inhibitors.