Extracorporeal lung assist (ELA) has been recommended for the treatment of ARDS if conventional therapy fails. However, the need for nearly complete anticoagulation is a major risk factor for hemorrhagic complications. We describe our experience with 13 ARDS patients treated with ELA using heparin-coated systems (Carmeda). Maintaining partial thromboplastin time and activated clotting time within or close to the normal range, even major surgery (20 thoracotomies and 2 laparotomies) could be performed without undue bleeding complications related to anticoagulation during extracorporeal support. Eight of the 13 patients survived. The use of heparin-coated systems allows prolonged ELA with nearly physiological coagulation function, permitting major surgical intervention. It enhances the safety margin of extracorporeal gas exchange and may ultimately extend its indications.