OBJECTIVE: To evaluate the safety/tolerability and efficacy of tegaserod, a 5-HT4 receptor partial agonist, in the treatment of patients with non-diarrhoea irritable bowel syndrome (non-D-IBS) in Switzerland. METHODS: This was an 8-week, open-label, prospective, multicentre study. Patients (> or =18 years old) met the Rome II diagnostic criteria for IBS, excluding those with diarrhoea for > or =14 days in the previous 3 months. Details of IBS symptoms experienced in the preceding week were recorded at visit 1 (day 1). Eligible patients received 6 mg tegaserod twice daily for 8 weeks. Adverse events (AEs) and serious AEs were recorded, along with detailed assessment of diarrhoeal episodes. Efficacy assessments included the overall number and percentage of responders after 8 weeks' treatment. RESULTS: A total of 850 patients (72% women; mean age, 51.4 years) were enrolled, and 843 received at least one dose of tegaserod. AEs were reported in 38% of patients, of which 13% were drug-related. Diarrhoea occurred early during treatment (13% in the first week, 7% thereafter), was mild to moderate in severity, was transient and was resolved with continued treatment. In total, 208 patients left the study early, primarily due to AEs. Diarrhoea accounted for 68 of these discontinuations. Nine serious AEs were reported but these were not related to tegaserod treatment. Sixty-six percent of patients responded to tegaserod on the Subject's Global Assessment of relief after 8 weeks. Benefits were also seen across individual IBS symptoms. CONCLUSION: Tegaserod (6 mg twice daily) appears to be safe, well-tolerated and effective in the treatment of non-D-IBS over 8 weeks.