Objective:To summarize the clinical features, treatments and outcomes of patients with SMARCB1(INI-1)-deficient sinonasal carcinoma (SDSC).Methods:Fifteen patients who were diagnosed as SDSC in Beijing Tongren Hospital from October 2016 to June 2021 were retrieved, including nine males and six females, ranged from 25 to 78 years old. For TNM stage, one case was in stage T2, one case was in stage T3, 13 cases were in stage T4; 13 cases were in stage N0, two cases were in stage N2; 14 cases were in stage M0, one case was in stage M1. The most common paranasal sinus affected by tumor was the ethmoid sinus. Five patients were treated by radical surgical resection combined with postoperative adjuvant therapy, four patients treated by neoadjuvant therapy with surgical resection, three patients treated by surgical resection only, one patient treated by neoadjuvant therapy with concurrent chemoradiotherapy, one patient treated by preoperative radiotherapy with surgery, and one patient received palliative chemotherapy. Immunohistochemical analysis was performed in all cases. The Kaplan-Meier method was used to draw the survival curve, and the Log-rank test was used to compare the difference to 20 undifferentiated carcinoma patients with positive INI-1 expression in the same period.Results:Immunohistochemical analysis showed the complete absence of INI-1 expression in the tumor nuclei in all 15 cases. The follow-up information was available with a median follow-up time of 21 months (3-56 months). The 3-year overall survival rate, disease specific survival rate, disease-free survival rate and metastasis-free survival rate were 58.9%, 58.9%, 36.4% and 31.2%, respectively. Disease-free survival in SDSC patients was significantly lower compared with undifferentiated carcinoma patients with positive INI-1 expression ( HR=2.87,95% CI:0.92~8.91, P=0.043). Cox regression analysis showed that patients with comprehensive treatment based on surgery had a better prognosis than others ( HR=8.61,95% CI:1.38~53.73, P=0.021). Conclusion:SDSC is a highly aggressive malignant tumor with the characteristics of easy recurrence, early metastasis and poor prognosis. INI-1 immunohistochemical analysis is recommended in the pathologically poorly differentiated sinonasal carcinoma. Comprehensive treatment based on radical resection may be the first choice for SDSC patients.