Artificial liver support systems were developed to remove potential toxins from the circulation of patients with liver failure. A wide range of substances have been implicated in the toxic manifestations of liver failure, but no substance(s) has been identified as being of key importance. Charcoal haemoperfusion appeared to be beneficial in early studies, but when clinical trials were performed in 137 patients at King's College Hospital there was no significant improvement in survival over intensive care alone. There have been many studies using haemodialysis/filtration systems, where an improvement in conscious level of the patient was reported, but the effect on survival was less clear. Recently in Japan, continuous high volume haemofiltration with the addition of plasma exchange has been used to support liver failure patients. In liver failure, endotoxaemia and increased cytokine production are important in the pathogenesis of circulatory failure. Experiments on adsorbents to remove cytokines have shown that Amberlite XAD-7 resin can remove significant amounts of tumour necrosis factor and interleukin-6 from liver failure plasma. The development of hepatocyte bioreactors with synthetic and metabolic function for clinical use will be a major advance in liver support.