Amplification of CCND1 was studied in 23 tongue carcinoma patients by fluorescence in situ hybridization (FISH) using a paraffin embedded specimen. All the patients received complete resection of the primary site with or without neck dissection. CCND1 amplification was positive in 13 (56.5%) out of 23 cases. Correlations between CCND1 amplification and histological grading, T category, N category, and Stages were not significant. The 5-year disease-free survival rate, which was 23.1% for CCND1 amplification positive patients and 80.0% for negative patients, was significantly better for the CCND1 amplification negative patients (P=0.0070). Nine patients were examined by dual-color FISH with the probe for centromere of chromosome 11 and 11q13. In five patients, who had positive amplification for CCND1, cell numbers with a larger number of signals for 11q13 than the centromere of chromosome 11 were significantly higher than those of CCND1 amplification negative patients (P=0.013). This indicates that amplification of 11q13 occurs more frequently than aberration of chromosome 11 in CCND1 amplification positive patients. From these results, the amplification of CCND1 is a key factor in predicting the aggressiveness of tongue cancer. Furthermore, FISH proved to be a useful method for such evaluation.