Objective: To describe our experience with the use of extracorporeal membrane oxygenation (ECMO) as a rescue therapy in adult patients with severe cardiopulmonary failure from Hantavirus pulmonary syndrome., Design: Case series., Setting: Tertiary referral center., Patients: Patients with confirmed Hantavirus infection, who developed severe cardiopulmonary failure in which conventional therapy was assessed as being unsuccessful., Interventions: Records of previous patients treated for Hantavirus pulmonary syndrome were reviewed and findings consistent with 100% mortality were found., Measurements and Main Results: Findings associated with a 100% mortality rate were a) cardiac index of <2.5 L/min/m2; b) serum lactate concentration of >4.0 mmol/L (normal range 0.0 to 2.2); c) pulseless electrical activity or ventricular fibrillation or ventricular tachycardia; and d) refractory shock despite fluid resuscitation, and vasoactive medications. From 1994 to 1996, seven patients were admitted with confirmed Hantavirus pulmonary syndrome and severe cardiopulmonary failure. Three of the seven patients had at least two of the four criteria for a 100% mortality rate listed above, and appeared to be failing optimal conventional therapy. These three patients received support with venoarterial ECMO. The first patient was placed on ECMO during cardiac arrest and died. The next two patients who received ECMO for Hantavirus pulmonary syndrome survived after relatively short, uncomplicated ECMO runs, and were discharged without complications., Conclusions: ECMO successfully provided cardiopulmonary support in two patients with severe Hantavirus pulmonary syndrome who survived with a good outcome. Our experience suggests that ECMO is a beneficial therapy for patients critically ill with Hantavirus pulmonary syndrome.