Goals: To assess if curcumin improves markers of cholestasis among subjects with primary sclerosing cholangitis (PSC). Background: PSC is a chronic cholestatic liver disorder for which there is no established medical therapy. Preclinical data suggest curcumin may have a beneficial effect in PSC. Study: Subjects with PSC and a serum alkaline phosphatase (SAP) greater than 1.5 times the upper limit of normal (ULN) received curcumin 750 mg orally twice daily for 12 weeks in an open-label pilot study. The primary composite endpoint was proportion of subjects who had a reduction of SAP to less than 1.5 times ULN or a 40% reduction in SAP between baseline and week 12. Secondary endpoints included changes in serum aspartate aminotransferase, total bilirubin, Mayo PSC risk score and self-reported health questionnaires. Results: Two-hundred and fifty-eight patients with PSC were screened and 15 subjects were enrolled and all completed 12 weeks of therapy. The most common reason for subject exclusion was SAP less than 1.5 times the ULN (n = 98). Curcumin did not result in a significant median (interquartile range) change in SAP times the ULN [3.43 (2.10-4.32) to 2.46 (1.89-4.41), p = .36], and only 20% (3/15) subjects achieved the primary endpoint. Similarly, there was no significant change in the secondary endpoints. There were no serious adverse events reported. Conclusion: While curcumin was well tolerated, it was not associated with significant improvements in cholestasis or symptoms. Moreover, this study also illustrates that a low SAP is common among those with PSC. Abbreviations PSC: Primary sclerosing cholangitis; IBD: inflammatory bowel disease; CCA: cholangiocarcinoma; SAP: serum alkaline phosphatase; ULN: upper limit of normal; UDCA: ursodeoxycholic acid; CRP: c-reactive protein; AST: aspartate aminotransferase; ALT: alanine aminotransferase; INR: international normalized ratio; FIS: fatigue impact scale; AE: adverse events; PREsTo: PSC risk estimate tool; IQR: interquartile range; ELF: enhanced liver fibrosis.