Objective To construct a nomogram to effectively predict the prognosis of patients with gallbladder carcinoma after radical resection. Methods The nomogram was based on retrospectively collected data from 832 patients with gallbladder carcinoma after radical resection at the SEER (Surveillance, Epidemiology, and End Results Program) database from 2004 to 2013. The data was divided into a training set (n=608) and a validation set (n=224) by random sampling. The Cox proportional hazard regression model was performed to identify the independent risk factors affecting prognosis. The nomogram was developed based on the training set. The comprehensive survival probability scores of each patient were obtained based on the nomogram, and the results were internally validated by 1 000 bootstrap resampling with the training set and externally validated with the validation set. The predictive accuracy of the nomogram was determined by concordance index (C-index) and calibration curve. Results The median disease-specific survival (DSS) of training dataset was 22.07 months and the postoperative 1-, 3-, and 5-year DSS rates were 67.6%, 36.8%, and 29.2%, respectively. Multivariate analyses demonstrated that sex, age, grade, lymph node metastasis, tumour size, extension range and metastasis were independent risk factors for DSS. The C-index of internal validation for DSS prediction was 0.76 (95%CI 0.74~0.78), which was superior to the AJCC (American Joint Commission on Cancer) staging system [0.70, 95%CI 0.67~0.73, P<0.001]. The calibration curves for the probability of postoperative DSS at 5 years suggested 

that there was a good consistency between the actual observation and the prediction. Conclusion The nomogram developed in this study can accurately and intuitively predict individual DSS of patients with gallbladder carcinoma after radical resection.