101 outpatients with irritable bowel syndrome were randomly allocated to two treatment groups. Both groups received the same medical treatment, but patients in one group also received dynamically oriented individual psychotherapy in ten hour-long sessions spread over 3 months. After 3 months there was a significantly greater improvement in somatic symptoms in the psychotherapy group. The difference became more pronounced a year later, with the patients given psychotherapy showing further improvement, and the patients who received medical treatment showing some deterioration. The combination of medical treatment with psychotherapy improves outcome, not only in the short term but also in the long run.