OBJECTIVE: To evaluate the oncologic outcomes of patients with sinonasal cancer treated with endoscopic resection. DESIGN: Retrospective review. SETTING: Tertiary care academic cancer center. PATIENTS: All patients with biopsy-proved malignant neoplasm of the sinonasal region who were treated with endoscopic resection between 1992 and 2007 were included in the study, and their charts were reviewed for demographics, histopathologic findings, treatment details, and outcome. MAIN OUTCOME MEASURES: Oncologic outcomes, including disease recurrence and survival. RESULTS: Of a total of 120 patients, 93 (77.5%) underwent an exclusively endoscopic approach (EEA) and 27 (22.5%) underwent a cranioendoscopic approach (CEA) in which the surgical resection involved the addition of a frontal or subfrontal craniotomy to the transnasal endoscopic approach. Of the 120 patients, 41% presented with previously untreated disease, 46% presented with persistent disease that had been partially resected, and 13% presented with recurrent disease after prior treatment. The most common site of tumor origin was the nasal cavity (52%), followed by the ethmoid sinuses (28%). Approximately 10% of the tumors had an intracranial epicenter, most commonly around the olfactory groove. Tumors extended to or invaded the skull base in 20% and 11% of the patients, respectively. An intracranial epicenter (P < .001) and extension to (P = .001) or invasion of (P < .001) the skull base were significantly more common in patients treated with CEA than in those treated with EEA. The primary T stage was evenly distributed across all patients as follows: T1, 25%; T2, 25%; T3, 22%; and T4, 28%. However, the T-stage distribution was significantly different between the EEA group and the CEA group. Approximately two-thirds (63%) of the patients treated with EEA had a lower (T1-2) disease stage, while 95% of patients treated with CEA had a higher (T3-4) disease stage (P < .001). The most common tumor types were esthesioneuroblastoma (17%), sarcoma (15%), adenocarcinoma (14%), melanoma (14%), and squamous cell carcinoma (13%). Other, less common tumors included adenoid cystic carcinoma (7%), neuroendocrine carcinoma (4%), and sinonasal undifferentiated carcinoma (2%). Microscopically positive margins were reported in 15% of patients. Of the 120 patients, 50% were treated with surgery alone, 37% received postoperative radiation therapy, and 13% were treated with surgery, radiation therapy, and chemotherapy. The overall surgical complication rate was 11% for the whole group. Postoperative cerebrospinal fluid leakage occurred in 4 of 120 patients (3%) and was not significantly different between the CEA group (1 of 27 patients) and the EEA group (3 of 93 patients) (P > .99). The cerebrospinal fluid leak resolved spontaneously in 3 patients, and the fourth patient underwent successful endoscopic repair. With a mean follow-up of 37 months, 18 patients (15%) experienced local recurrence, with a local disease control of 85%. Regional and distant failure occurred as the first sign of disease recurrence in 6% and 5% of patients, respectively. The 5- and 10-year disease-specific survival rates were 87% and 80%, respectively. Disease recurrence and survival did not differ significantly between the EEA group and the CEA group. CONCLUSIONS: To the best of our knowledge, this is the largest US series to date of patients with malignant tumors of the sinonasal tract treated with endoscopic resection. Our results suggest that, in well-selected patients and with appropriate use of adjuvant therapy, endoscopic resection of sinonasal cancer results in acceptable oncologic outcomes.