Background. Diffi cult bile duct stones of over 15 mm diameter cause choledocholithiasis in signifi cant num- bers of patients. This condition requires the use of techniques such as mechanical lithotripsy (ML) which are more complex than sphincterotomy and which also require more time to accomplish. This increases the potential for complications. Objective. To describe our experience with attempted papillary dilations with large balloons to treat diffi cult bile duct stones. Design. Observational study. Descriptive research. Case series. Results. Endoscopic retrograde cholangiopancreatography (ERCP) and LBPD procedures were attempted in 20 patients aged 43 to 91. Of these patients 11 were men, and 14 were women. ERCPs and ESTs had previously been performed on 14 of these patients (70%), while this was the fi rst time for the other 6 patients (30%). Indications for performing LBPDs were bile duct stones ≥ 15 mm in 11 patients (55%), disproportion between common the bile duct and the papillary orifi ce in 12 patients (60%), and both conditions in 3 patients (15%). The total success rate for resolution of choledocholithiasis was 95%. Removal of bile duct stones in a single session was accomplished in 17 patients (85%) while two additional sessions each were required to remove the stones in two patients (10%). It was not possible to completely remove one patient's stones (5%) endoscopically. Only 7 patients (35%) required lithotripsy. The total complication rate was estimated at approximately 10%. One patient (5%) presented a small amount of bleeding after the sphincterotomy, but no intervention was required. Another patient (5%) presented a mild post-ERCP pancreatitis which evolved satisfactorily. Conclusions. This is the fi rst case series report of the use of LBPD to treat diffi cult bile duct stones as a new alternative for resolving choledocholithiasis. It obtained a 95% success rate. Thanks to this technique, we avoided treatment with mechanical lithotripsy in 65% of these cases and also obtained an acceptable rate of complications. The clinical fi ndings reported in this study correlate well other case series reports and clinical trials published in the literature. Although this is a preliminary study, these results suggest that the LBPD is a safe and effective technique for treating diffi cult bile duct stones.