This study aimed to analyse whether age, metastasis, extrathyroidal invasion and size (AMES) risk definition is valuable for Japanese patients with differentiated thyroid carcinoma (DTC). Methods: Two hundred and fifteen Japanese DTC patients (43 men, 172 women; mean age, 51.0 years; mean follow-up, 102 months) treated surgically at our institutions between 1981 and 2001 were retrospectively analysed. Clinicopathological features were compared between high-risk and low-risk patients by AMES criteria. Various risk factors were also evaluated for each group of patients. Results: There were 57 high-risk and 158 low-risk patients. Recurrence and mortality rates were 43.9% and 24.6% in high-risk patients and 7.6% and 0.6% in low-risk patients, respectively (p < 0.0001). Disease-specific survival rates at 5, 10 and 15 years were 84.3%, 74.0% and 63.5% in high-risk patients and 100%, 100% and 98.3% in low-risk patients, respectively (p < 0.0001). Univariate analysis revealed that curative resection, local recurrence and distant metastasis were risk factors for mortality in the high-risk group. Multivariate analysis revealed that curative resection (hazard ratio [HR], 4.68; 95% confidence interval [CI], 1.23-17.83; p = 0.024) and distant metastasis (HR, 4.79; 95% CI, 1.24-18.40; p = 0.023) were significantly related to mortality in high-risk patients. Conclusion: AMES can identify high-risk and low-risk Japanese patients. Distant metastasis and curative resection are prognostic factors for disease-specific death.