Abstract. Objective: To compare rocuronium and succinylcholine for rapid-sequence intubation (RSI) in the emergency department (ED). Methods: A oneyear prospective cohort comparison study was performed using a data collection form completed at the time of intubation. Data collected included the reason for the neuromuscular-blocking agent (NMBA) chosen, the time to onset of paralysis, and any complications encountered. Three ten-point numerical descriptor scales recorded the degree of body movement, vocal cord movement, and the physician's overall satisfaction with the extent of paralysis. Results: Succinylcholine was used in 382 patients and rocuronium was used in 138 (26% of all RSI) patients. The mean (Ϯ SD) times of onset of succinylcholine and rocuronium were 39 Ϯ 13 sec and 44 Ϯ 20 sec, respectively (p = 0.04). No patient desaturated and required assisted ventilations while waiting for paralysis to occur. Types of body movements were similar with the two agents, but less frequent with succinylcholine (median = 10, mean = 9.5 Ϯ 1.1) than rocuronium (median = 10, mean = 9.1 Ϯ 1.5) (p = 0.01). Vocal cord movements were similar for succinylcholine (median = 10, mean = 9.2 Ϯ 1.6) and rocuronium (median = 9, mean = 9.0 Ϯ 1.6) (p = 0.15). The physician's overall satisfaction with the extent of paralysis was also higher for succinylcholine (median = 10, mean = 9.4 Ϯ 1.3) than rocuronium (median = 10, mean = 8.8 Ϯ 2.0) (p < 0.01). Only one complication, widening of the QRS complex secondary to succinylcholine use in a patient with unsuspected hyperkalemia, could be attributed to the choice of NMBA. Conclusions: Both succinylcholine and rocuronium produced fast and reliable paralysis for RSI. Although succinylcholine had a faster onset and provided more relaxation, the difference had no clinical significance. Approximately a fourth of ED RSI patients qualified for use of rocuronium using these high-risk criteria. Key words: rapid-sequence intubation; tracheal intubation; neuromuscular-blocking agents; succinylcholine; rocuronium. ACADEMIC EMERGENCY MEDICINE 2000; 7:1362-1369 R APID-sequence intubation (RSI) is a lifesaving procedure developed to quickly and safely secure the airway of a critically ill or injured patient. In the emergency department (ED), RSI is often chosen over other intubation techniques because the simultaneous onset of deep sedation and paralysis, followed rapidly by tracheal intubation, minimizes the risk of pulmonary aspiration of gastric contents. Rapid-sequence intubation has therefore become the technique of choice for the intubation of patients at risk of having full stomachs, such as ED patients. Indeed, several recent studies have shown RSI as the most common method to achieve airway control in the ED.