Lymphoma, which represents about 5.4% of all neoplasms and, more significantly, 19% to 28% of malignant neoplasms, is the most common nonepithelial malignancy of the head and neck area in Koreans. Natural killer T-cell (NK/T-cell) lymphoma is a lymphoma of putative natural killer cell lineage. NK/T-cell neoplasms are generally rare, but they are more common in people of East Asian, Mexican, or South American descent. These neoplasms are highly aggressive and show a strong association with Epstein-Barr virus. The preferential site of extranodal NK/T-cell lymphoma is the nasal cavity, and there has been no report of NK/T-cell lymphoma developing from the tongue. We encountered a rare case of NK/T-cell lymphoma of the tongue, which we report with a review of the literature.