It has been considered that oral cancer is cured if more than five years pass without recurrence or metastasis after the initial treatment. Treatment results are usually evaluated as a 5-year survival rate, but we sometimes find recurrence more than five years after the initial treatment. We retrospectively investigated treatment results by long-term follow-up of advanced squamous cell carcinoma of the oral cavity after radical surgery, and analyzed the relation between the period of follow-up and the time to recurrence. One hundred and sixteen patients with advanced squamous cell carcinoma of the oral cavity were enrolled between November 1994 and October 2004 in this study. Seventy-six patients were Stage III and 40 were stage IV, and the mean age of this cohort was 63.0 years. All patients received radical surgery with or without preoperative chemoradiotherapy and were followed for a minimum of 5 years. Overall actuarial survival of all patients was 77.8% at 10 years. The 10-year cumulative local and regional recurrence rates were 20.1% and 12.9%, respectively. The actuarial loco-regional recurrence rate was the highest within 2 years after initial treatment at 19.0%, and was seen in 3.4% even after 5 years. These results showed that it is necessary to follow-up patients with advanced oral cancer even beyond 5 years after the initial treatment because there was delayed loco-regional recurrence in 3.4%.