A device for treating a biological liquid has a housing with a first chamber defining a cavity and which is adapted to receive a liquid to be treated. At least one gas exchanger is at least partly disposed in the first chamber. An inlet portion is formed in a first surface of the housing for the inlet of the liquid to be treated into the chamber. The inlet portion is formed at an acute angle relative to the surface of the housing. Such a device allows a gas exchange in a lung assist method for example.
