Paracetamol overdose (POD) is a major clinical problem as the commonest cause of fulminant hepatic failure (FHF) in the UK and the USA. While the main loss of liver mass occurs following hepatocyte necrosis, hepatocyte apoptosis has also been reported to occur during paracetamol toxicity in murine liver. Hepatocyte apoptosis has not previously been identified in human liver and the significance of apoptosis in paracetamol toxicity is not known. In this study of paracetamol toxicity in human liver after POD, hepatocyte apoptosis was identified at time of liver transplantation or death and was associated with striking regenerative activity. The biological significance of apoptosis is unclear but the rates of apoptosis found (0.6%) could account for a significant loss of hepatic parenchyma. The stimulus for apoptosis is not known but it is unlikely to be induced directly by paracetamol since it is absent from serum at this time. The possibility that apoptosis may be induced by Kupffer cell activation with cytokine production is raised. Patients who develop FHF after POD have a poor prognosis, with few therapeutic options apart from liver transplantation; an understanding of the dynamics of liver regeneration and ongoing cell loss by apoptosis may allow the development of new therapies in these patients.