BACTERIAL OVERGROWTH IS MORE COMMON THAN SUSPECTED 202 patients with IBS underwent hydrogen breath testing 202 patients with IBS underwent hydrogen breath testing 157 (78%) had SBBO and were treated with antibiotics 157 (78%) had SBBO and were treated with antibiotics 25/47 patients had normal breath tests at follow-up 25/47 patients had normal breath tests at follow-up Diarrhea and abdominal pain were significantly improved by treatment Diarrhea and abdominal pain were significantly improved by treatment