Purpose As there were few previous studies with a small number of subjects, the purpose of this was to evaluate the prognostic significance of 18 F-FDG PET/CT in patients with distal bile duct cancer undergoing curative surgery. Methods The study included 40 patients (M/F = 24:16; age 68.0 ± 8.0 years) who underwent preoperative 18 F-FDG PET/CT followed by curative surgical resection. The participant's age, sex, Eastern Cooperative Oncology Group performance-status score, baseline serum CA 19-9 level, stage, pathologic T and N stages, tumor size, tumor grade, tumor growth pattern, R0 resection, and adjuvant therapy were included as clinicopathological variables for predicting overall survival. The PET variables were maximum standardized uptake value (SUV max), average SUV (SUV avg), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the tumor. The Kaplan-Meyer method and Cox proportional hazards model were used for the survival analysis. Results A total of 15 of 40 patients (37.5%) died during the follow-up period. In univariate analysis, low SUV max (≤ 2.7, p = 0.0005) and low SUV avg (≤ 2.6, p = 0.0034) were significant predictors of poor overall survival. In multivariate analyses, only low SUV max (HR = 6.7016, 95% CI 1.9961-22.4993, p = 0.0047) was an independent prognostic factor associated with poor overall survival. Conclusion The SUV max of the primary tumor measured by 18 F-FDG PET/CT was an independent significant prognostic factor for overall survival in patients with distal bile duct cancer. However, different results from a previous study warrant further large sample-sized study.