According to the AJCC 2002 staging system, squamous cell carcinoma of the oral cavity (OSCC) with T4b is unresectable. Herein, we report on our surgical outcome for T4b OSCC. All patients were enrolled before 2002. From January 1996 to December 2000, 45 consecutive untreated T4b OSCC patients were included. According to the trans-axial plane of the mandibular notch on CT/MRI, seven were supra-notch T4b and 38 were infra-notch T4b tumors. Significantly higher 5-year loco-regional control and survivals were observed in patients with infra-notch T4b than with supra-notch T4b. In the infra-notch group, pN0-1 patients had a significantly higher 5-year loco-regional control and survivals than pN2 patients. Nerve invasion was the sole significant adverse factor for loco-regional control and survivals in the infra-notch T4b group with pN0-1. Our retrospective study demonstrated that OSCC patients of infra-notch T4b with pN0-1 and no nerve invasion might have a favorable surgical outcome.