Hepatitis B and C viruses have been implicated in a few cases of acute liver failure attributed to sporadic (community acquired) non-A, non-B hepatitis, but reports are conflicting. We determined whether hepatitis B virus and hepatitis C virus were detectable in prospectively stored hepatectomies from seven British patients grafted for acute liver failure attributed to sporadic non-A, non-B hepatitis. For hepatitis B virus, we used nested polymerase chain reaction with primers to the core and surface regions. For hepatitis C virus, we used one round of reverse transcription polymerase chain reaction with primers to the 5' untranslated region and Southern hybridization using an internal oligonucleotide probe as well as nested PCR for the E1 region. Positive controls were native livers from two patients with unequivocal fulminant hepatitis B and from four patients with cirrhosis attributed to hepatitis C virus. Our negative findings suggest that, in the UK, acute liver failure attributed to sporadic non-A, non-B hepatitis most likely is caused by agent/s other than hepatitis B and C viruses.