Objectives/Hypothesis: The purpose of this study was to investigate survival differences between low-grade and high-grade sinonasal adenocarcinoma (SNAC) by examining demographics, tumor characteristics, and treatment modalities.Study Design: Retrospective database analysis. Methods: The National Cancer Database was queried for patients with SNAC between 2004 and 2015. Univariate and multivariate analyses were performed for all cases of SNAC. Subsequent analysis focused on low-grade (grade 1 and grade 2) and high-grade (grade 3 and grade 4) SNAC.Results: A total of 1,288 patients with SNAC were included in the main cohort and divided into low grade (n = 601) and high grade (n = 370). The 5-year overall survival for all patients, low-grade, and high-grade was 54%, 64%, and 38%, respectively. Prognostic factors associated with decreased survival for the main cohort include advanced age (hazard ratio [HR]: 1.04; 95% confidence interval [CI]: 1.03-1.06), Charlson-Deyo score (HR: 1.37; 95% CI: 1.05-1.78), grade 2 (HR: 2.21; 95% CI: 1.26-3.86], grade 3 (HR: 3.67; 95% CI: 2.09-6.45), and grade 4 (HR: 3.31; 95% CI: 1.38-7.91). Radiotherapy was associated with improved overall survival for high-grade SNAC (HR: 0.41; 95% CI: 0.24-0.70) but not for low-grade SNAC (HR: 1.05; 95% CI: 0.59-1.85).Conclusions: This investigation is the largest to date analyzing the association of treatment modalities with overall survival in SNAC. Surgery remains paramount to treatment, with radiotherapy offering additional survival benefit for high-grade SNAC. Administration of chemotherapy was not associated with improved survival.