We report the bench testing of three new anaesthesia ventilators: Flexima (Datex), SA2/RA2 and Cato (Dräger). The test circuit included a two compartment lung model, a pneumotachograph and a pressure gauge. Volume was integrated from flow signal. The tidal volume delivered by the Flexima and SA2/RA2 ventilators decreased with increasing mechanical work load contrarily to the Cato. Moreover, the tidal volume of the Flexima increased with the fresh gas flow. In spontaneous ventilation inspiratory resistance were low.