Background: Myoclonic movements are a common problem during the induction of general anesthesia with etomidate. We investigated the influence of pretreatment with the opioid sufentanil on the incidence of etomidate-induced myoclonus. Methods: Forty female patients (ASA physical status I–III) were randomly assigned to receive double-blinded either 0.3 µg kg−1 of sufentanil or placebo 150 s before the induction of sleep with 0.3 mg kg−1 of etomidate. The patients were observed for any myoclonic movement. Grade of dizziness, breathing frequency, non-invasive blood pressure and heart rate were measured during the study period. Results: None of the 20 patients receiving sufentanil had myoclonic movements after the administration of etomidate, whereas 16 patients in the placebo group (80%) experienced such movements (P<0.01). No cases of apnoea before induction of sleep were seen in the sufentanil group. Conclusion: Sufentanil 0.3 µg kg−1 is an effective and safe drug to reduce myoclonus after etomidate without causing any harmful side-effect.