Endoscopic retrograde cholangiopancreatography (ERCP) is frequently used to clear the common bile duct (CBD) in patients with choledocholithiasis. While a single ERCP is usually effective, many patients undergo multiple ERCP attempts before cholecystectomy. Here we sought to identify preoperative factors predictive of surgical complexity beyond routine laparoscopic cholecystectomy after ERCP. Data were prospectively collected for all ERCPs between September 2010 and February 2012 at a public academic medical center including demographics, indication, stone presence, CBD diameter, sphincterotomy, stent placement, and ERCP number. A total of 124 ERCPs were attempted in 73 patients with choledocholithiasis, 10 per cent of whom presented with cholangitis. Fifty-six per cent of patients underwent one ERCP, whereas 16 per cent required ≥ 3 procedures. Laparoscopic cholecystectomy was performed in 58 (79%) patients whereas 15 (21%) patients required more complex operations including eight open CBD explorations and two hepaticojejunostomies. The likelihood of requiring more complex surgery correlated with increasing number of ERCPs with an adjusted odds ratio of 5.75 (95% confidence interval: 2.31-14.3, P ≤ 0.001). Increased CBD diameter also correlated with complex surgery with adjusted odds ratio of 1.5 (95% confidence interval: 1.10-2.06, P = 0.012) for each millimeter. The number of preoperative ERCPs and CBD diameter in choledocholithiasis patients are strong predictors of the need for open surgery and CBD exploration and should be considered in surgical planning and consent for patients requiring more than one ERCP procedure.