OBJECTIVE: To examine the hypothesis that pediatric resuscitation providers hyperventilate patients via bag-valve-mask (BVM) ventilation during performance of cardiopulmonary resuscitation (CPR), quantify the degree of excessive ventilation provided, and determine if this tendency varies according to provider type. METHODS: A retrospective, observational study was conducted of 72 unannounced, monthly simulated pediatric medical emergencies ("mock codes") in a tertiary care, academic pediatric hospital. Responders were code team members, including pediatric residents and interns (MDs), respiratory therapists (RTs), and nurses (RNs). All sessions were video-recorded and reviewed for the rate of BVM ventilation, rate of chest compressions, and the team members performing these tasks. The type of emergency, location of the code, and training level of the team leader were also recorded. RESULTS: Hyperventilation was present in every mock code reviewed. The mean rate of BVM ventilation for all providers in all scenarios was 40.6 ± 11.8 breaths per minute (BPM). The mean ventilation rates for RNs, RTs, and MDs were 40.8 ± 14.7, 39.9 ± 11.7, and 40.5 ± 10.3 BPM, respectively, and did not differ among providers (P = .94). All rates were significantly higher than the recommended rate of 8 to 20 BPM (per Pediatric Advanced Life Support guidelines, varies with patient age) (P < .001). The mean ventilation rate in cases of isolated respiratory arrest was 44.0 ± 13.9 BPM and was not different from the mean BVM ventilation rate in cases of cardiopulmonary arrest (38.9 ± 14.4 BPM; P = .689). CONCLUSIONS: Hyperventilation occurred in simulated pediatric resuscitation and did not vary according to provider type. Future educational interventions should focus on avoidance of excessive ventilation. Copyright © 2011 by the American Academy of Pediatrics.