Duodenogastric reflux is quantified in ten patients with biliary lithiasis and a functioning gallbladder, before and six months after performing cholecystectomy. The results are compared with those of a control group (n = 10) with similar age and gender, without gastric or hepatobiliary pathologic factors. To evaluate reflux, we used six hour continuous intravenous infusion and subsequent determination in gastric juice of 99mTc-diethyliminodiacetic acid. Our results showed that patients with cholelithiasis have higher reflux rates than those in the control group (p < 0.001). When comparing patients before and after cholecystectomy, we confirmed that removal of the gallbladder produces a significant increase (p < 0.001) in reflux rates compared with preoperative values.