Inclusion Criteria:

• Both genders
• Females of childbearing age must have negative pregnancy test within 48 hours of participation and agreement to practice contraception for the duration of the study.
• Age 18 years old and < than 75 years old.
• History of chronic cholestatic disease of at least 6 months duration.
• Serum alkaline phosphatase level at least 1.5 times the upper limit of normal.
• Cholangiography demonstrating intrahepatic and/or extrahepatic biliary obstruction, beading, or narrowing consistent with PSC.
• Liver biopsy consistent with the diagnosis of PSC.
• Patient's informed consent for study participation.

Exclusion Criteria:

• Treatment with tetracyclines, ursodeoxycholic acid, corticosteroids, colchicine, methotrexate, azathioprine, cyclosporine, chlorambucil, budesonide, pentoxifylline, perfenidone, nicotine, tacrolimus, silymarin, vitamin E or prednisone in the preceding three months.
• Findings highly suggestive of hepatobiliary disease of other etiology complicating PSC.
• Anticipated need for liver transplantation in one year determined by the Mayo model with an estimate of <75% one year survival without transplantation.
• Recurrent variceal bleeding, presence of ascites, or encephalopathy.
• Active drug or alcohol use.
• Pregnancy.
• Breast-feeding.
• Serum creatinine over 1.5 mg/dl.
• Prior history of allergic reactions to antibiotics belonging to the tetracycline family.
• Any condition that, in the opinion of the investigator, would interfere with the patient's ability to complete the study safely or successfully.
• Patients with active inflammatory bowel disease (IBD) requiring specific treatment in the preceding three months, except for maintenance therapy with 5-ASA compounds, or those individuals who have been involved in a trial evaluating any experimental drug for the treatment of IBD in the preceding three months.
• Recurrent ascending cholangitis requiring hospitalization in the past year.