Background/aim: Biliary stents have been used for benign or malignant biliary strictures, preoperative biliary drainage, resolution of biliary or pancreatic leaks, and dissolution treatment of non-extractable bile duct stones since 1979, and should be replaced at 3-6 month intervals. The aim of this cross-sectional pioneer study was to identify the in microorganisms in occluded bile duct stents and to determine incidence and diagnosis of multidrug resistance of the isolated microorganisms in stents and in blood cultures. Methods: Fifty-one patients (14F, 37M, mean age: 58.2 +/- 11.6 yr) with cholangitis due to occluded stents were studied consecutively and prospectively after stent replacement was done. Independent variables were age, gender, underlying disease, duration of disease, size, length and period of stents, and blood biochemistry. Dependent variables were microorganisms isolated from the stent content and blood of the patients and the results of antibiogram tests. Results: Primary disease was malignant in 25 (49.0%), stent size was 7F in 30 (58.8%), and stent length was 11 cm in 11 (21.6%) and 15 cm in 12 (23.5% of the patients. The mean period after the 1(st) stent application was 207.0 +/- 111.3 days and the last stent duration was 111.0 +/- 64.0 days. Isolated microorganisms from stents and blood, respectively, were Escherichia coli (E. coli) (43.4%, 20.8%), Klebsiella spp.. (17.1%, 17.0%), Pseudomonas aeruginosa (P. aeruginosa) (13.2%, 18.9%) and Enterococcus spp. (10.5%, 17.0%). Isolated microorganisms showed multidrug resistance at high percentages (81.6% for stent, 81.1% for blood). ALT, AST, ALP, and direct bilirubin levels showed statistically significant differences between the benign and malignant groups. Conclusion: All bile duct stents are contaminated by microorganisms, of which a high majority has multidrug resistance, and they frequently cause biliary sepsis. Biliary sepsis call be prevented by changing the stents periodically and by using proper antibiotic prophylaxis.