The Irritable bowel syndrome (IBS) is a highly prevalent functional disorder with a remarkable clinical and economic impact. Several pathogenetic factors of IBS are discussed and summarised within a bio-psycho-social model. Data from published hypnotherapeutic interventions with approximately 800 patients show long-lasting symptom relief. The underlying mechanisms of action are not well understood. Nine mechanism studies show influences of hypnosis on colorectal sensitivity, colorectal motility and mental strain (anxiety, depression, maladaptive cognitions). Results are often contradictory and effects of hypnosis on several of the proposed pathogenetic factors are not examined at all. This paper reviews previous studies on hypnotherapy in IBS patients with a focus on symptom relief and mechanisms of action.