 Eligible patients are selected by a gastroenterologist for the study inclusion criteria: age 18-60, fulfilment of Rome II criteria, abdominal pain episodically reaching 4 on a 0-10 VAS, and stable symptoms for the past 2 years. A thorough clinical work-up is done to exclude organic disease, including routine blood and electrolyte status, hepatic enzyme function and lactose tolerance test as well as colonoscopy or colon x-ray. Patients with significant somatic or psychiatric co-morbidity will be excluded. 