We studied the recovery of rats with fulminant hepatic failure (FHF) by treating them with our original hybrid artificial liver support system (HALSS). FHF was induced by a two-thirds partial hepatectomy and 10 minutes of hepatic ischemia. Rats with FHF were treated with a polyurethane foam/spheroid HALSS including 2.0 x 10(8) hepatocytes for 1 hour (HALSS group, n = 5), and with the same system without hepatocytes in the artificial liver module as a control experiment (sham-HALSS group, n = 3). The level of blood constituents, ammonia, glucose and creatinine, showed no major difference between the two groups at the end of treatment. All rats in the sham-HALSS group died within 5 hours after treatment. However, the level of blood constituents of rats with FHF in the HALSS group improved with time, and all rats in the HALSS group recovered. Liver tissue of rats treated with HALSS showed cell mitosis and improvement from injury. These results indicated that our HALSS has a strong possibility to induce recovery from hepatic failure.