Extranodal NK/T-cell lymphoma is a rare disease entity with aggressive clinical course and poor prognosis. Currently, there is no treatment option for relapsed or refractory extranodal NK/T-cell lymphoma. Romidepsin is a histone deacetylase inhibitor which was approved for cutaneous T-cell lymphoma. A recent phase II study of romidepsin for relapsed/refractory peripheral T-cell lymphoma reported an overall response rate of 38% (95% confidence interval 24%-53%). The median duration of overall response was 8.9 months. Considering the median number of previous treatments in these patients was three (range 1-11), romidepsin has single agent activity against relapsed/refractory T-cell lymphoma. Thus, if the single agent activity of romidepsin is demonstrated, it could be a therapeutic agent for combination with salvage treatment.