Crohn's disease is a chronic inflammatory granulomatous disorder affecting any part of the gastrointestinal tract, particularly the terminal ileum and the colon. Familiar complications are strictures, fistulae, perforation, haemorrhages and malabsorption due to multiple resections. A patient with two rare complications of Crohn's disease is described. A 16-year-old female with ileocaecal Crohn's disease presented with anaemia and ileus. This ileus was caused by some 40 tablets of ferrosulphate with a non-soluble matrix, in the presence of an existing stenosis of the ileum due to Crohn's disease. An ileocaecal resection was performed. During an exacerbation of Crohn's disease she developed hepatic vein thrombosis with a Budd-Chiari syndrome (upper abdominal pain, hepatomegaly and ascites). Prescription of tablets with a non-soluble matrix is contraindicated in patients with a partial stenosis of the intestine. Patients with active Crohn's disease are predisposed to thromboembolic complications. Hepatic vein thrombosis in our patient may have been the result of hypercoagulability during the exacerbation of her disease.