Abstract Background: The current opinion is that the reflux of jejunal juice over the whole length of a long Roux-en-Y jejunal loop is very uncommon. We aimed to challenge this concept by monitoring the presence of bile in the organ proximal to a 60-cm loop during a 24-hour period with use of the Bilitec device, an optoelectronic instrument capable of measuring absorbance of a beam of light, the wavelength of which is close to the absorbance peak of bilirubin. Patients and methods: Forty-one patients, 8 of whom had been cholecystectomized, were investigated after total gastrectomy (group I, n = 17), distal gastrectomy (group II, n = 7), or duodenal switch (group III, n = 17). The percentage of recording time absorbance >0.25 (absorbance scale ranging from 0 to 1) was calculated in reference to data from healthy subjects. Results: Bile was detected in 17 patients (41%), 5 belonging to group I, 2 to group II, and 10 to group III ( P = 0.165). Bile exposure remained within the range of controls in 14 patients whereas it was above this range in 3 patients, 2 of whom had disabling heartburn and severe esophagitis. The percentage of time absorbance >0.25 did not significantly differ from one group to another ( P = 0.257) or according to whether patients had been cholecystectomized or not ( P = 0.439). However, unlike cholecystectomized patients, patients still having their gallbladder refluxed predominantly during postprandial periods. Lengthening of the loop from 60 cm to 110 cm in the 2 symptomatic patients with a pathologic bile reflux resulted in relief of heartburn and healing of esophagitis in both while bile reflux was abolished in 1 and dramatically reduced in the other. Conclusions: Bile refluxes over the whole length of 4 Roux-en-Y loops out of 10. In most patients, bile reflux remains within the range of healthy subjects, producing neither symptoms nor mucosal damage; and it occurs independently of the organ proximal to the loop, but its timing of occurrence is modified by cholecystectomy. Although only for exceptional indications, lengthening of an incompetent loop is effective in patients with excessive bile reflux and severe related symptoms and lesions.