The output of sevoflurane from a drawover system utilizing two Oxford Miniature Vaporizers (OMVs) in series has been shown in bench-testing to be predictable. We have shown that adequate anaesthesia can be achieved with one vaporizer in most situations if an intravenous induction is used. Occasionally a second vaporizer is necessary to deepen the level of anaesthesia. For an inhalational technique to be successful it is necessary to use both vaporizers from the outset. Under these conditions, adequate operating conditions are easily produced. The method could be useful in field or military applications.