SummaryThe primary goal of' this study was to assess the influence of clonidine administered after induction on postoperative shivering after elective peripheral surgery. The effect of clonidine on intra-operative haemodynamics (blood pressure and heart rate) during thejirst 30min after induction and on the postoperative sedation of the patient was also investigated. Two hundred and eighty male ASA 1 and 2 patients, undergoing elective peripheral surgery were randomly administered either placebo or clonidine 2 pg.kg-' intravenously over 10 min after induction of anaesthesia. Clonidine was found to reduce the total incidence (p = 0.024, the severity (p = 0.005) and the duration (p = 0.01) of postoperative shivering. Clonidine did not increase postoperative sedation or diminish overall consciousness. We conclude that administration of clonidine 2 pg.kg-' intravenously after induction of anaesthesia is safe and reduces postoperative shivering in this group of patients. Key wordsComplications; shivering. Pharmacology; clonidineRecovery from anaesthesia and surgery is frequently accompanied by involuntary muscular activity. Besides the discomfort for the patient, shivering can exacerbate postoperative pain and induce complications in patients with coronary artery disease or heart failure by increasing oxygen consumption [I] To date, no unequivocal direct evidence has been published to show that preventive pre-or postoperative administration of clonidine reduces postanaesthetic shivering after peripheral surgery. This large, randomly administered, double-blind study was performed to evaluate the influence of clonidine administered at induction on postoperative shivering after elective peripheral surgery. The effect of clonidine on intra-operative haemodynamics (blood pressure and heart rate) during the first 30 min after