The alpha agonist dexmedetomidine, a sedative and analgesic, reduces heart rate and blood pressure dose-dependently. We investigated whether it also has the ability to attenuate airway and circulatory reflexes during emergence from anaesthesia. Sixty ASA I-III patients received a standard anaesthetic. Five minutes before the end of surgery, they were randomly allocated to receive either dexmedetomidine 0.5 microg/kg (Group D) (n=30) or saline placebo (Group P) (n=30) intravenously (i.v.) over 60 s in a double-blind design. The blinded anaesthetist awoke all the patients, and the number of coughs per patient was continuously monitored for 15 min after extubation; coughing was evaluated on a 4-point scale. Any laryngospasm, bronchospasm or desaturation was recorded. Heart rate (HR) and systolic and diastolic blood pressure (SAP, DAP) were measured before, during and after tracheal extubation. The time from tracheal extubation and emergence from anaesthesia were recorded. Median coughing scores were 1 (1-3) in Group D and 2 (1-4) in Group P (P<0.05), but there were no differences between the groups in the incidence of breath holding or desaturation. HR, SAP and DAP increased at extubation in both groups (P<0.05), but the increase was less significant with dexmedetomidine. The time from tracheal extubation and emergence from anaesthesia were similar in both groups. These findings suggest that a single-dose bolus injection of dexmedetomidine before tracheal extubation attenuates airway-circulatory reflexes during extubation.