Eleven patients were treated with the Hepatix extracorporeal liver assist device (ELAD) between June 1991 and August 1993. The first 2 patients were treated according to Food and Drug Administration guidelines ("Emergency Use of Unapproved Medical Devices," October 22, 1985), and the remaining 9 were treated according to an Investigational Device Exemption (IDE). The goal of the study was to establish the short-term safety of ELAD therapy, with a focus on acute medical complications such as hemodynamic instability, complement activation, and deterioration of vital organ function. As secondary goals, the metabolic capacity of ELAD cartridges and their clinical impact were assessed. Treatment was considered successful if the patient recovered sufficient liver function to survive weaning from the ELAD or was stabilized until orthotopic liver transplantation was performed. No short-term safety problems were associated with ELAD use. In addition, metabolic support was documented in 10 of the 11 patients, and 6 patients reached a successful end-point. The Hepatix ELAD is safe, and it provides measurable metabolic support in patients with late-stage liver failure. This pilot study provides the impetus to perform controlled trials of ELAD therapy in the treatment of various types of end-stage liver disease.