BACKGROUND: COPA (cuffed oropharyngeal airway) is a convenient device for airway management in patients undergoing general anesthesia for elective surgery in supine position. It causes less pharyngeal trauma than LMA (Laryngeal mask airway). The purpose of this study was to compare the effect of COPA with and without muscle relaxant. METHODS: Forty patients with ASA physical status I and II for elective surgery were randomly assigned to two groups. Anaesthesia was induced with propofol (2 mg/kg) and vecuronium (1.5 mg/kg) and was administered intravenously in Group I but not in Group II. Mask ventilation was done for 5 min with O2 5 L/min. COPA was placed and heart rate, and systolic, mean, diastolic blood pressure and peak inspiratory pressure were measured at 1 min interval for 5 min. Anaesthesia was maintained with propofol 150 microgram/kg/min, fentanyl 1 microgram/kg/hr, O2 2 L/min and N2O 2 L/min. RESULTS: There were no significant differences between Group I and Group II in heart rate, systolic, mean and diastolic blood pressure. PIP (Peak inspiratory pressure) was increased and hiccups occurred significantly (p < 0.05) in Group II. Complete airway obstruction occurred in one patient of Group I and severe coughing, body movements and gagging occurred during induction and insertion in Group II. CONCLUSIONS: With the use of appropriate muscle relaxant, we can use COPA without increased inspiratory pressure or significant complication.