BACKGROUND/AIMS: Peroral cholangioscopy is a rapidly evolving technique that allows direct examination of the bile duct. We sought to determine if there was a difference in image quality with the cholangioscope immersed in normal saline compared with radiologic contrast or a mixture of contrast and normal saline. METHODS: Images were captured using the SpyGlass(R) cholangioscope system (Boston Scientific Corp.) immersed in solutions ranging from 0 to 100% contrast. The images were then reviewed in a blinded fashion by a panel of 9 endoscopists with experience using the SpyGlass(R) system. The reviewers scored the quality of each image based on a scale of 0 (extremely poor) to 10 (excellent). RESULTS: With the cholangioscope immersed in saline and 100% contrast, the mean image quality scores were 7.6 (95% confi dence interval [CI], 6.7-8.5) and 6.9 (95% CI, 5.8-8.0), respectively. The highest mean image quality score was 7.8 (95% CI, 6.7-8.9), obtained in 70% contrast. No signifi cant difference was noted in mean image quality scores using a one way analysis of variance technique (p=0.414). CONCLUSIONS: Although there are limitations to ex vivo studies, we encourage endoscopists to use intraductal contrast prior to peroral cholangioscopy, if needed for lesion localization.