Data on balloon enteroscopy-assisted ERCP (BEA-ERCP) versus laparoscopy-assisted ERCP (LA-ERCP) in post-Roux-en-Y gastric bypass (RYGB) patients are lacking. To compare BEA-ERCP with LA-ERCP in post-RYGB patients and to identify factors that predict therapeutic success with BEA-ERCP. Retrospective chart review. A single North American tertiary referral center. The review included 56 bariatric post-RYGB patients who underwent ERCP. BEA-ERCP or LA-ERCP. Cannulation rate, therapeutic success, hospital stay, complications, procedure duration, endoscopist time, and cost. A total of 32 patients underwent BEA-ERCP, and 24 underwent LA-ERCP. LA-ERCP was superior to BEA-ERCP in papilla identification (100% vs 72%, P = .005), cannulation rate (100% vs 59%, P < .001), and therapeutic success (100% vs 59%, P < .001). The total procedure time was shorter (P < .001) and endoscopist time was longer (P = .006) for BEA-ERCP. There was no difference in postprocedure hospital stay (P = .127) or complication rate (P = .392) between the 2 groups. In the BEA-ERCP group, in patients having a Roux limb + biliopancreatic (from ligament of Treitz to jejunojejunal anastomosis), a limb length less than 150 cm was associated with therapeutic success. Starting with BEA-ERCP and continuing with LA-ERCP after a failed BEA-ERCP saved $1015 compared with starting with LA-ERCP. Single center, retrospective study. In centers with expertise in deep enteroscopy and ERCP, post-RYGB patients with a Roux + ligament of Treitz to jejunojejunal anastomosis limb length less than 150 cm should first be offered deep enteroscopy-assisted ERCP. In patients with Roux + ligament of Treitz to jejunojejunal anastomosis (LTJJ) limb length 150 cm or longer, LA-ERCP should be the preferred approach because of the lack of need for a second procedure, equivalent morbidity and hospital stay, decreased endoscopist time, and decreased cost.