Conclusions: Our findings demonstrate a clinically relevant impact of syringe size on syringe infusion pump performance at low flow rates. The time to reach 50% and 90% of target flow are significantly longer, using the 50-mL syringe compared with the 10-mL syringe, and the time to reach 50% of target flow is independent of the longer start-up delay. Based on our findings, we speculate that smaller syringe sizes and higher infusion rates are preferable for continuous drug infusions, particularly when prompt establishment of the drug effect is critical. (Pediatr Crit Care Med 2010; 11: 282-286)