A randomized, double-blind, placebo-controlled trial was performed to evaluate the efficacy and safety of AST-120 in nonconstipating IBS. 115 patients were randomly allocated to receive AST-120 (2 g three times daily) or placebo. AST-120 was found to be safe and well-tolerated. Although AST-120 reduced pain and bloating, these beneficial effects might be limited in duration. Further studies of this novel agent are warranted.