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Background. – Hepatitis B vaccination is recommended for chronic kidney disease (CKD) patients before starting dialysis. We performed an analyis aimed to describe the clinical and biological parameters related to the success of vaccination in CKD patients before starting dialysis. Methods. – We extracted data of 170 non-dialyzed patients who were offered hepatitis B vaccination from a register. They received a first vaccination of 40 mg followed by boosters after one, two and six months. Patients were considered protected if their hepatitis B antibody level was > 10 IU/L, three months apart. A logistic regression and a Bayesian model were used to describe the relationships between variables and the success of vaccination. Results. – Vaccination protected 50.6% of the patients. Model adjustment to the data was higher using the Bayesian model compared to the logistic regression (with area under the ROC curve of 0.955 ± 0.007 vs 0.775 ± 0.066 respectively). The Bayesian model’s robustness studied using a 10 fold cross validation showed a percentage of misclassified subjects of 12.4 ± 1.8%, a sensitivity of 87.7 ± 0.3%, a specificity of 87.5 ± 0.3%, a positive predictive value of 87.8 ± 0.3% and negative predictive value of 87.4 ± 0.2%. As classified by the Bayesian model, the variables most related to successful vaccination were, in descending order: age, eGFR, protidemia, albuminemia, cause of renal failure, gender, previous vaccination and weight. Conclusion. – The Bayesian network confirmed that both kidney function and nutritional status of patients are important factors to explain the success of vaccination against hepatitis B in CKD patients before dialysis. For research purposes, before an external validation, the network can be used online atwww.hed.cc/?s=Bhepatitis&n=ReseauhepatiteBsup10.neta.