The present invention relates to an expiratory valve (10) of a ventilation device (100), comprising a valve body (12) having a fluid inlet (14) and a fluid outlet (16) for breathing air of a patient formed therein, said valve body (12) defining a fluid flow path between fluid inlet (14) and fluid outlet (16), with the cross-sectional area of said fluid flow path expanding in the direction towards the fluid outlet (16).
