The effectiveness of Bentyl (dicyclomine hydrochloride) 40 mg 4 times daily was evaluated in an ambulatory population with recent irritable bowel syndrome (IBS). During the 2-week double-blind study, the effects of dicyclomine hydrochloride compared to placebo were assesed by: 1) physicians' global evaluation of treatment, 2) patients' self-evaluation of treatment, and 3) patients' evaluation of duration of abdominal pain. It was concluded that over a 2-week period dicyclomine hydrochloride 40 mg 4 times a day is superior to placebo in improving the overall condition of the patient, decreasing abdominal pain, decreasing abdominal tenderness, and improving bowel habits. The majority of adverse effects reported were related to the anti-cholinergic activity of the drug.