A 54-year-old woman presented with a nasal mass. Biopsy demonstrated undifferentiated tumor cells with extensive apoptosis and necrosis. Chromosome analysis identified a 46,XX,t(15;19)(q13;p13.1) pattern. Nuclear protein in testis (NUT) immunohistochemistry and fluorescence in situ hybridization confirmed NUT rearrangement. A Ewing sarcoma–based chemotherapy regimen and concurrent irradiation obtained a dramatic response; however, the patient died of her disease less than 7 months after initial diagnosis. NUT midline carcinomas are rare, aggressive tumors defined by rearrangement of the NUT gene on 15q14. A solitary translocation involving 15q14 is usually the sole chromosomal abnormality in these carcinomas. Immunohistochemical expression of NUT in the nuclei of non–germ cell tumors is theoretically diagnostic. More widespread use of a newly available NUT immunohistochemical stain will facilitate the diagnosis of NUT rearranged carcinomas. From the growing numbers of identified cases, effective targeted therapies can be developed.