Abstract: A device for use in the sampling or infusion of liquids from or to the human or animal body having a first connecting means (8) for connection to a cannula, a second connecting means (13) for connection to a source or drain of liquid and valve means (4,9) operable to open or close a flow path therebetween, the arrangement being such that in a closed condition of the valve means each of the connecting means is connected to a respective chamber (6, 7), each chamber having a respective venting means (20, 21) allowing the escape of air therefrom while preventing the escape of liquid and such that in an open condition of the valve means a flow path is established from one connecting means to the other through at least one of the chambers. The device allows connection to be made without spillage and removes air from the liquid.