Demand for magnetic resonance investigations in critically ill patients is increasing. While these patients frequently need ventilatory support, not all of them require controlled ventilation and many may be treated with continuous positive airway pressure. Controlled ventilation, with the concurrent need for sedation, may be inappropriate when airway physiology is being studied and may retard weaning. No commercially available ventilator designed for the magnetic resonance environment can deliver high flow continuous positive airway pressure. We tested the Caradyne Whisperflow flow generator and five Whisperflow valves (2.5-15 cmH2O airway pressure) within a 3 Tesla environment for safety and possible dysfunction. All components had minimal ferromagnetic properties and tests showed no clinically relevant change in flow delivery or oxygen concentration in the magnetic field. In addition, the airway pressure generated by the valves was not affected by the magnetic field. We conclude that the tested system can be safely used in a 3 Tesla magnetic resonance environment.