Background. Despite the widespread use of both two paramedic and single paramedic ambulance crews, there is little evidence regarding differences between these two staffing configurations in the delivery of patient care. Objectives. To determine potential differences in care provided by each of these ambulance configurations in the resuscitation of a cardiac arrest victim in ventricular fibrillation. Methods. Fifteen paramedic-paramedic and 15 paramedic-EMT crews were recruited to perform resuscitation on a high-fidelity human simulator (Laerdal SimMan™). Errors and their nature, time to critical interventions, and compliance with continuous cardiopulmonary resuscitation (CPR) were captured by the simulator and videotape. Results. Two paramedic crews averaged 0.7 ± 0.5 more errors of commision, 0.5 ± 0.4 more errors of sequence, and 0.8 ± 0.8 more total errors per resuscitation (± 95% CI; p = 0.008, 0.017, and 0.036, respectively). For all interventions analyzed, only time required to achieve intubation differed between the two configurations, with two paramedic crews intubating 63.9 ± 45.8 seconds more quickly (p = 0.009). CPR compliance was highly variable, and a meaningful statistical difference could not be determined, although performance overall was poor, with both configurations averaging less than 50% compliance. Conclusion. Two paramedic crews were more error-prone and did not perform most interventions more rapidly with the exception of intubation. These data do not support the proposition that two paramedic crews provide higher quality cardiac care than paramedic-EMT crews in a simulated ventricular fibrillation arrest. [ABSTRACT FROM AUTHOR]