BACKGROUND: Propofol is commonly used for providing procedural sedation during pediatric colonoscopy. Intravenous (i.v.) lidocaine can mitigate visceral pain and reduce propofol requirements during surgery. The aim of this study is to investigate the effect of i.v. lidocaine on perioperative propofol and sufentanil dose, pulse oxygen saturation, postoperative pain score, and recovery time during pediatric colonoscopy. METHODS: We designed a randomized, double-blind, placebo-controlled study and enrolled 40 children aged from 3 to 10 years who underwent colonoscopy. After titration of propofol to achieve unconsciousness, the patients were given i.v. lidocaine (1.5 mg/kg later 2 mg/kghour) or the same volume of saline. Sedation was standardized and combined propofol with sufentanil. The primary outcome variables were intraoperative propofol and sufentanil requirements, and the number of oxygen desaturation episodes. Secondary outcome variables were recovery time after colonoscopy and post-colonoscopy pain. RESULTS: Lidocaine infusion resulted in a significant reduction in propofol requirements: (median (quartile) 1.8 (1.5-2.0) vs. 3.0 (2.8-3.3) mg/kg respectively; P < 0.001) and sufentanil requirements: (median (quartile) 0.06 (0.05-0.08) vs. 0.1 (0.1-0.1) μg/kg respectively; P < 0.001). The number of subjects who experienced oxygen desaturation below 95% in the lidocaine group was also significantly less than that in the control group: 1 vs. 6 (P = 0.04). The mean (SD) recovery time was significantly shorter in the lidocaine group: (19.2 (2.6) vs. 13.3 (2.6) min respectively; P < 0.001). There was no significant difference in post-colonoscopy pain. CONCLUSION: Continuous infusion of lidocaine resulted in reduction of propofol and sufentanil requirements, recovery time, and risk of hypoxemia during pediatric colonoscopy.