"Overlap syndromes" have been reported among various autoimmune liver diseases, particularly between primary biliary cirrhosis and autoimmune hepatitis (AIH) in adults and between AIH and autoimmune cholangitis in children. The overlap syndrome of AIH and primary sclerosing cholangitis (PSC), however, has been scarcely reported. Furthermore, in most of the reported cases of AIH/PSC overlap syndrome, PSC and AIH were believed to occur simultaneously. We report a case of a 34-year-old woman who has ulcerative colitis and PSC (diagnosed by colonoscopy, histology, and cholangiogram) and 7 years later develops rapidly progressive liver failure and hemolytic anemia from AIH. Liver biopsy showed dense portal lymphoplasmacytic infiltrate with interface hepatitis and acidophil bodies confirming AIH. She responded well to immunosuppressive therapy with steroids, both with respect to her liver disease and her autoimmune hemolytic anemia. Additionally, her clinical symptoms of fatigue, jaundice, and pruritus improved markedly and quickly. Overlap or "crossover" syndrome should be considered in all patients with PSC when they present with sudden deterioration of the liver function and changes in liver enzymes. By making the diagnosis of AIH in a patient with well-established PSC, appropriate treatment can be initiated, resulting in the patient's prompt recovery.