Certain conditions may necessitate use of neuromuscular blocking agents (NMBAs) in children in the pediatric intensive care unit (PICU). Despite information concerning individual agents, there are limited studies comparing agents. I compare 4 of the more commonly used NMBAs: pancuronium, vecuronium, rocuronium, and atracurium. All agents were administered by bolus followed by a continuous infusion with the rate adjusted by use of a peripheral nerve stimulator to maintain one twitch of the train-of-four. Ten patients with normal hepatic and renal function were included in each group. The study period included the first 72 hours of neuromuscular blockade. All 4 agents were easily titrated by continuous infusion to maintain the desired level of blockade. Pancuronium infusion requirements varied from 0.03 to 0.12 mg/kg/hr, vecuronium requirements from 0.05 to 0.2 mg/kg/hr, rocuronium requirements from 0.5 to 1.9 mg/kg/hr, and atracurium requirements from 0.8 to 2.2 mg/kg/hr. No significant advantage of one agent over another was noted. The wide range of infusion requirements further stresses the need for close monitoring of the degree of neuromuscular blockade with a peripheral nerve stimulator. An additional 10 patients with abnormal hepatic/renal function received atracurium. The dose requirements were the same as in patients with normal end-organ function, ranging from 0.6 to 2.0 mg/kg/hr. In patients with abnormal hepatic or renal function, atracurium may be used without the need to alter the dose.