Some hypnotics may interact with neuromuscular blockers and potentiate their effects. This study aimed at evaluating the influence of propofol and etomidate on rocuronium-induced neuromuscular block. Participated in this study 60 patients, physical status ASA I and II, scheduled for elective surgeries under general anesthesia, who were randomly distributed in two groups according to the hypnotic drug: Group I (propofol) and Group II (etomidate). All patients were premedicated with intramuscular midazolam (0.1 mg.kg-1), 30 minutes before surgery. Anesthesia was induced with propofol (2.5 mg.kg-1) or etomidate (0.3 mg.kg-1) preceded by alfentanil (50 microg.kg-1) and followed by rocuronium (0.6 mg.kg-1). Patients were ventilated under mask with 100% oxygen until achieving a decrease of 75% or more in the adductor pollicis muscle response amplitude. Neuromuscular function was monitored by accelerometry. The following parameters were evaluated: rocuronium onset (T1 <= 25%); time for complete neuromuscular block; neuromuscular block degree at tracheal intubation; tracheal intubation conditions and hemodynamic effects. Complete rocuronium-induced neuromuscular block onset times (in seconds) were: Group I (48.20 +/- 10.85 s and 58.87 +/- 10.73 s) and Group II (51.20 +/- 13.80 s and 64.27 +/- 18.55 s). Neuromuscular block degree at tracheal intubation was: Group I (77.50%) and Group II (76.96%). Tracheal intubation conditions were satisfactory in 100% of Group I patients and in 83.33% of Group II patients. There has been a significant decrease in mean blood pressure, followed by an increase after hypnotic injection, in both groups. Propofol and etomidate had a similar behavior regarding time for rocuronium-induced neuromuscular block and tracheal intubation conditions.52673-80