OBJECTIVES: To conduct an exploration of the hospital costs of extracorporeal life support therapy. Extracorporeal life support seems an efficient therapy for acute, potentially reversible cardiac or respiratory failure, when conventional therapy has been inadequate, or as bridge to transplant, but unfortunately, no evidence in randomized controlled trials is delivered yet. DESIGN: Single-center retrospective exploratory cohort cost study. The study is performed from a hospital perspective with a time horizon of patients' complete hospital admission in which they received extracorporeal life support. SETTING: ICU of a university teaching hospital in The Netherlands. PATIENTS: All 67 consecutive adult patients who were admitted to the ICU of the University Medical Center Groningen in the period 2010-2013 and received extracorporeal life support treatment. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: The bottom-up microcosting method was used except when stated otherwise. Medical costs were estimated by multiplying every registered healthcare consumption with unit prices. Unit prices were largely based on Dutch reference prices. For each patient, the personnel costs and material costs were assessed in detail. The costs of extracorporeal life support were differentiated in costs of procedures and costs of daily surcharge of therapy. Procedure-related costs were subdivided in costs of devices and disposables, costs of additional human resources, and surgery hours. The mean total hospital costs were € 106.263 (€ 83.841 to € 126.266) per patient ($145,580). On average, 52% of the total costs arose from hospital nursing days and 11% of direct procedure-related extracorporeal life support costs. Surgery and diagnostics represented a vast amount of the remaining costs. CONCLUSIONS: This large and detailed economic evaluation of hospital costs of extracorporeal life support therapy in the Netherlands showed that mean total hospital cost of extracorporeal life support treatment is € 106.263 per patient. The majority of the costs are composed of nursing days.