1. In a retrospective study, we stratified 79 patients with paracetamol hepatotoxicity into two groups according to weekly alcohol consumption below (n = 49) or above (n = 30) Royal College of Physicians' guidelines of 21 units week-1 for males and 14 for females. 2. Survival was lower (33%) and serum creatinine on admission higher (median 207 mumol) in patients whose alcohol consumption was above recommended guidelines than in those whose drank less than this (65.9% and 138 mumol, P less than 0.01 and P = 0.027, respectively). An arterial blood pH less than 7.30 on admission was also more common in those patients with a higher alcohol consumption (30% v 12.2%, P = 0.05). 3. In all patients whose alcohol consumption exceeded the guidelines, paracetamol overdose was fatal if associated with a serum creatinine greater than 300 mumol in conjunction with a prothrombin time over 100 s and grade 3 or 4 encephalopathy or a peak prothrombin time over 180 s. 4. Chronic alcohol intake above suggested limits is an adverse prognostic feature in cases of severe paracetamol overdose. This effect is partly related to increased nephrotoxicity.