Objective To analyze the results of 18F-fluorodeoxyglucose (18F-FDG) coincidence imaging and prognosis in postoperative patients of tongue cancer. Methods 18F-FDG coincidence imaging was performed in 90 patients with pathologically confirmed tongue cancer no less than 3 months after surgical therapy. The diagnostic ability of coincidence imaging in detecting recurrence and/or metastasis of tongue cancer was assessed. Survival rates were calculated by Kaplan-Meier method. Logrank test was used in univariate prognostic analysis. Cox regression model and stepwise regression backward maximum likelihood method were used in multivariate prognostic analysis. Results The sensitivity, specificity, accuracy, positive (PPV) and negative predictive values (NPV) of 18F-FDG coincidence imaging for detecting recurrence and/or metastasis of tongue cancer were 95.1% (58/61), 69.0% (20/29), 86.7% (78/90), 86.6% (58/67) and 87.0% (20/23), respectively. Of the 34 patients with recurrence of tongue cancer, tongue body (32.4%, 11/34) was the most frequent recurrent locations. Of the 40 patients with metastasis of tongue cancer, lymph node (65.1%, 41/63) was the main site of metastases. Then lung (27.0%, 17/63) and bone (6.3%, 4/63) followed. The 1-, 3- and 5-year overall survival rates of 90 postoperative tongue cancer patients were 82.5%, 54.7% and 52.9%, respectively. Univariate analysis showed that TNM stage, degree of histological differentiation, early lymphatic metastasis, local recurrence and distant metastasis were significantly relevant to prognosis of tongue cancer (χ2=26.282, 9.629, 9.629, 9.442, 4.928, respectively, all P<0.05). Multivariate analysis indicated that TNM stage, degree of histological differentiation, early lymphatic metastasis, local recurrence, delayed lymphatic metastasis and distant metastasis were independent risk factors influencing prognosis (Wald value=9.855, 6.585, 5.042, 6.271, 4.354, 5.134, respectively, all P<0.05). Conclusion 18F-FDG coincidence imaging may be an effective noninvasive technique for postoperative monitoring and prognosis prediction of tongue cancer.