The utility of ursodiol in primary sclerosing cholangitis is somewhat controversial. While ursodiol has been associated with improvements in biochemical indices of liver function, it has yet to be shown to consistently reverse or retard progression of liver disease (8). Therefore, it is critical to know the rationale for prescribing ursodiol only for a subset of patients and at relatively low dosages (approximately 9 to 10 mg/kg per day compared with more standard dosing of 13 to 15 mg/kg per day). In addition, time to progression, as well as long-term follow-up assessing the efficacy of ursodiol against colorectal cancer or other clinically relevant events (for example, frequency of endoscopic evaluations, intensity of the biopsy protocol, or colectomy), would have been of considerable relevance. For example, if ursodiol were shown to delay and ultimately reduce the incidence of dysplasia, the case for its preventive potential would be stronger. Finally, the argument could have been strengthened further through the inclusion of biomarkers assessing ursodiol pharmacokinetics or pharmacodynamics (for example, mucosal kinetics or changes in concentrations of serum and fecal bile acids) to confirm patient adherence, agent bioavailability, and biological effects.