Background: When calculating differences between interventions, direct cost comparisons are typically based on Medicare reimbursement rates. The additional out-of-pocket costs of the patient have been little studied in endoscopy. Aim: To determine out-of-pocket costs for patients undergoing ERCP. Methods: Between June and August 2009, all outpatients referred to our tertiary care university hospital for elective ERCP were prospectively interviewed regarding out-of-pocket costs for procedures. Patients were asked regarding any costs to undergo the procedure including co-pay, driving, parking, meals, child care or equivalent, and any additional expenses related to subsequent procedures or admissions related to the ERCP. Results: Over the study period, 94 outpatients (mean age 57 ± 16 years, 48% male) underwent ERCP. Mean/median out-of-pocket costs for the procedure were $177.97/72.54 and ranged from $0 to $2,033.54. The largest single expense for the procedure was related to copayment (median $75). Eleven patients required hospitalization for post-procedural complications resulting in additional median out-of-pocket costs of $25. Median hotel, food, and travel expenses were $171.00, $20.00, and $23.54, respectively. Conclusions: Out-of-pocket ERCP costs are not insignificant from the patient's perspective and should be added to the direct costs to calculate true procedure costs. © 2011 Springer Science+Business Media, LLC.