In 1987, we published a case series of a newly-described, highly malignant neoplasm, termed sinonasal undifferentiated carcinoma, in which treatment results were poor. In this updated study, we report the followup for the original three surviving patients and for six additional cases whose tumors were diagnosed between January 1987 and October 1991. These data suggest that the prognosis for patients with localized disease may be better than originally described.