Subfebrile temperatures and fever in acute stroke are associated with poor functional outcome. A 1 degree C rise in body temperature may double the risk of a poor outcome in patients who are admitted within 12 hours from the onset of symptoms. Two randomised double-blind clinical trials in patients with acute ischaemic stroke have shown that treatment with a daily dose of 6 g paracetamol results in a small but rapid and potentially worthwhile reduction of 0.3 degree C (95% CI: 0.1-0.5) in body temperature. It has been hypothesized that early antipyretic therapy reduces the risk of death or dependency in patients with acute stroke, even if they are normothermic. For this reason, a multicentre, randomized, double-blind clinical trial comparing high-dose paracetamol with placebo in 2500 patients has been launched. This study has been named 'Paracetamol (acetaminophen) in stroke' (PAIS). The primary outcome is death or dependency at three months. The study protocol is simple, and the amount of data to be gathered is limited. The trial will run for four years.