Background: An anaesthetic agent conserving device (ACD) has been added to a Bain system to approach the agent-saving capacity of a low flow circle system. Methods: Randomly selected ASA physical status I patients received a standardized anaesthetic with sevoflurane in air/O2 through either a circle system with 1.5 l/min fresh gas flow (n = 8), or through a Bain system with an added ACD with fresh gas flow 4.4–6.4 l/min (n = 8). A target controlled infusion of remifentanil was used for analgesia. Results: The median sevoflurane consumption was 19.7 and 22.0 ml/MAC/h with the low flow circle system and the Bain system + ACD, respectively (P=0.10, Mann–Whitney U-test), or when adjusted for weight 0.25 and 0.28 ml/MAC/h/kg (P=0.26, Mann–Whitney U-test). Conclusion: The expenditure of sevoflurane with a Bain system + ACD was close to that in a circle system with 1.5 l/min fresh gas flow. It is thereby possible to use sevoflurane to all its potential, performing for example rapid alterations in end-tidal concentration using high fresh gas flows by combining a Bain system with an ACD. Although the price is not decided for this not yet commercially available device, a potential for a lower cost exists. Additionally, there will be no concerns of toxic compounds produced in the absorber.