Assess and compare the accuracy of the current AJCC TNM staging system among a large population-based cohort with squamous cell carcinoma (SCC) of the base of tongue (BOT)/tonsil and other oropharyngeal (OP) subsites.Patients with OP SCC were identified using the Surveillance Epidemiology and End Results (SEER) database. Patients were classified according to the 6th edition AJCC TNM system, and also by primary site as follows: (1) BOT/tonsil (n=14,151), and (2) other oropharynx (n=1437). The Kaplan–Meier method was used to estimate 5-year disease-specific survival (DSS) in each AJCC TNM classification group. Analyses were then stratified according to primary site subgroups.Patients with BOT/tonsil tumors were more likely to be younger white males with higher N-stage and overall-stage tumors (p<0.001). Five-year DSS was nearly equal in AJCC Stage II and III OP SCC (Fig. 1). Although DSS was well-discriminated according to T and M classifications, discrimination according to N classification was poor and disconcordant between the two primary site subgroups. Overall (not shown), and in the BOT/tonsil group, N2a patients had significantly better DSS vs. those with N0/N1 disease (Fig. 2).The current AJCC classification system may need to be modified for BOT/tonsil tumors, especially regarding N stage. Unilateral nodal metastasis does not appear to uniformly denote a poor prognosis in OP SCC.