This Practice Point commentary discusses the findings and limitations of a study by Chey and colleagues that evaluated the safety and efficacy of tegaserod in women with mixed subtype IBS (alternating constipation and diarrhea) or constipation-predominant IBS. This trial, the largest performed in patients with mixed subtype IBS, demonstrated improvement in both global and individual IBS symptoms in patients treated with tegaserod (6 mg twice daily) compared with those receiving placebo. Tegaserod was generally well tolerated, with the most common adverse event being diarrhea. The limitations of the study include short duration (4 weeks) and the absence of men. This trial confirms the outcomes of previous studies demonstrating that pharmacologic modulation of the serotonin system can improve IBS symptoms in some patients. Unfortunately, the immediate clinical relevance of this study is now questionable, given the withdrawal of tegaserod from the US market in March 2007.