OBJECTIVE: To determine the efficacy and safety of tegaserod 6 mg b.i.d. in the treatment of constipation-predominant irritable bowel syndrome (C-IBS). METHODS: An 8-week, double-blind, randomized, parallel group, placebo-controlled, multicenter study in 510 Chinese patients who met the Rome II criteria for C-IBS. The study consisted of a 2-week baseline period, a 4-week randomized, double-blind treatment period with either tegaserod 6 mg b.i.d. or placebo (tegaserod:placebo = 1:1), followed by a 2-week withdraw period. Efficacy was assessed by patient's perception of overall symptoms of IBS during the previous week and severity of the patient's constipation during the last week and patient's assessment of their individual IBS symptoms. Safety was assessed by adverse events, laboratory evaluations, blood pressure and heart rates, Physical examination and ECG evaluations. RESULTS: The weekly severity of patients' perception of overall IBS symptoms was significantly lower in the tegaserod group from week 1 onwards and throughout the treatment period. The effects of tegaserod on secondary IBS efficacy parameters were consistently better in the tegaserod group starting in week 1 and lasting throughout the treatment period and withdraw period. Regarding adverse events during the treatment period, about 10% of the patients in the tegaserod group experienced an adverse event compared to 6% in the placebo group. Diarrhea, abdominal pain and dizziness were more frequent in the tegaserod group but had a low frequency. No serious adverse was observed due to tegaserod. CONCLUSIONS: Tegaserod 6 mg b.i.d. was effective in relieving overall IBS symptoms, constipation, abdominal discomfort and pain, bloating, etc with significant effects starting in week 1 and continuing throughout the treatment period. Tegaserod was generally well-tolerated and has no clinically relevant safety findings.