The effects on the sphincter of Oddi of intravenous administration of dipyrone, 2.5 g; tramadol, 50 mg; indomethacin, 75 mg; N-butylscopolamine, 20 mg; and nitroglycerin, 1 mg, in comparison to physiological saline were assessed in a single-blind study in 36 patients hospitalized with upper abdominal pain. Basal sphincter pressure and sphincter motility were measured for a 5-min period after treatment by endoscopic manometry. Nitroglycerin and dipyrone both caused a significant fall in basal sphincter pressure, while N-butylscopolamine and nitroglycerin produced a significant decrease in contraction frequency. Therefore, dipyrone, in contrast to tramadol and indomethacin, exhibits spasmolytic activity in addition to analgesia in biliary pain.