Azathioprine is a useful agent for the treatment of Crohn's disease but side effects occur in 10% of patients. Hepatic toxicity is well recognized and is usually associated with abnormalities of liver function tests. We describe a female patient who was on azathioprine for the treatment of Crohn's disease for a total of 216 months. She developed portal hypertension complicated by variceal haemorrhage. This required the insertion of a trans-jugular intra-hepatic porto-systemic shunt to control the bleeding. Subsequent histology has shown mild nodular regenerative hyperplasia, and other causes of liver disease have been excluded. The only liver function abnormalities were mild elevation of bilirubin and a low albumin in the later stages.