Cirrhosis resulting from autoimmune hepatitis is associated with an increased risk of hepatocellular carcinoma. A common treatment for autoimmune hepatitis, azathioprine, is also associated with the development of many other cancers, predominantly lymphomas. The strongest association is seen for post-transplant lymphoma and hepatosplenic T-cell lymphoma in Crohn's disease and ulcerative colitis patients; there is also an association with a variety of cutaneous malignancies. A relationship between azathioprine and sarcoma has not been demonstrated, though there have been sporadic case reports. We report here the development of leiomyosarcoma in a patient who was treated with azathioprine for autoimmune hepatitis without cirrhosis.