Background: Radiation therapy monotherapy (RT) is standard for patients (pts) with T2N0 squamous cell cancer (SCC) of the glottis. The presence of impaired vocal cord mobility (T2b) is known to portend higher failure rates compared to cancers with supra/sub-glottic extension without impaired cord mobility (T2a). This study sought to compare the local control (LC) rates for these pts and also compare them to LC rates in pts with T2b-3N0-2 glottic cancer treated with concurrent chemoradiotherapy (CRT). Methods: In this IRB approved retrospective review, we identified pts with histologically confirmed T2-3N0-2 invasive SCC of the glottis, treated with definitive RT or CRT from 1986 to 2013 at our institution. RT (mean dose 70Gy) was delivered using conventional opposed lateral fields; elective nodal irradiation was used for the majority of pts. Chemotherapy consisted of a 96 hour infusion of cisplatin and 5-fluorouracil on weeks 1 and 5, or single agent cisplatin q3wks. LC, overall survival (OS) and disease free survival (DFS) rates were calculated by the Kaplan-Meier method and compared between the groups using the Log-Rank test. Results: Among the 84 pts identified, RT alone was administered to 27 pts with T2aN0 and 31 pts with T2bN0. CRT was delivered to 26 pts with T2b-3N0-2. With a median follow-up of 34 months, we observed a 3-year LC rate in the T2bN0 pts treated with RT alone of 72.5%, compared to 95% in the T2aN0 pts treated with RT (p=0.01) and 91% in the T2b-3N0-2 pts treated with CRT (p=0.08). There was no difference in OS and DFS rates between the 3 groups. There were 13 local failures, 10 of whom were successfully surgically salvaged. On univariate analysis, lower performance status (p=0.04) and T2b disease treated with RT alone (p=0.02) were the only factors that were significantly associated with inferior LC. Patient age, tumor bulk, anterior commissure involvement, nodal stage and the type of chemotherapy were not associated with LC. The rates of acute and late toxicities were higher in the CRT group. Conclusions: Pts with T2bN0 glottic cancer have a relatively high rate of local failure with RT alone. CRT should be considered to maximize the likelihood of treatment success.