Single-operator cholangioscopy (SOC) is increasingly used for evaluation of the biliary tree following endoscopic retrograde cholangiopancreaticography (ERCP). This study aimed to determine the visual and histological success rates of SOC at a single Danish tertiary referral centre. All patients undergoing SOC between 2008 and 2015 were retrospectively included from a prospectively maintained database. Patient characteristics and proced-ure-related variables were obtained from medical records. A visual and a histological success rate were determined according to predefined criteria. In total, 54 patients underwent SOC, most often due to suspicion of malignancy (n = 53; 98%). In one case, access to the common bile duct failed, and in six cases malignant disease was missed. Thus, the cholangioscopies were successful in 47 of 54 procedures corresponding to a visual success rate of 87%. Nine patients (17%) had a mean of 1.3 ± 1.0 SOC-guided biopsies taken. The extracted tissue was inadequate for histological evaluation in seven of nine cases, corres-pond-ing to a histological success rate of 22% (two out of nine tissue samples were eligible for histological diagnosis). Considering the reasonable visual success rate, SOC seems to be a useful extension of ERCP during diagnostic work-up for detection of malignant disease in the biliary tree. However, one biopsy per patient is insufficient for histological verification of common bile duct malignancy. The Danish Health Authority (3-3013-1299/1) and The Danish Data Protection Agency (RH-2015-229). none.