The various definitions of acute liver failure do not accurately reflect the differences in clinical signs and prognosis. Liver support devices to improve the clinical condition before liver transplantation (LT) were used in 13 patients with primary nonfunction, 24 with fulminant hepatitis, 17 were affected by delayed nonfunction, and 56 of acute on chronic hepatic failure. The average age of these patients was 41.8 years. The average number of applications of molecular absorbing recirculating system (MARS) was about 6 (range: 1-24). The mean length of application was about 9 hours (range: 8-20). MARS treatment was carried out in HLF patients with continuous acute-on-chronic hepatic failure dialisate flow similar to continuous veno venus hemofiltration (CVVH), albumin flow < 20% of hematic flow, heparin 5/10 UI/kg. In acute on chronic hepatic failure (AoCHF) patients, 6- to 11-hour (average 8.5) treatments were performed for a minimum of three treatments. The majority of patients were treated in the intensive care unit (ICU). Laboratory results were also monitored and showed progressive modification: bilirubin (before treatment 22.37 +/- 11.6 mg/dL, after treatment 11.36 +/- 7.5 mg/dL) and ammonium (before treatment 238.2 +/- 19 microg/dL, after treatment 115.4 +/- 12 microg/dL) showed significant change (P < .01). Lactates (before treatment 3.48 +/- 1.3 mmol/L, after treatment 1.76 +/- 1.1 mmol/L) and creatinine (before treatment 2.36 +/- 0.18 mg/dL, after treatment 1.26 +/- 0.67 mg/dL) also showed significant changes (P < .02 and P < .04). Glasgow Coma Score (GCS) went from 8.6 +/- 1.4 to 11.9 +/- 3.9 (P < .05). The mean middle cerebral artery flow (V media) went from 46 cm/s/26-59) to 73 cm/s (52-106) representing decreased cerebral edema, a difference that was not significant. INR scores (before treatment 2.4 after treatment 1.8) also showed no significant change. The MARS can be applied with tolerability for long periods for patients with PDF and FH as a bridge to transplant. In patients with PDF, it is used for a waiting recovery of the transplanted organ. Therefore MARS can also limit the necessity to perform further transplants.