A device is provided for determining at least one parameter of a medium flowing in a line in a main flow direction, e.g., a parameter of the intake air mass of an internal combustion engine. The device includes a part, which is inserted into the line at a predetermined alignment with respect to the main flow direction in such a way that a partial flow of the medium flowing in the line in the main flow direction flows through at least one measuring channel provided in the part in a first direction from an intake of the measuring channel to an outlet of the measuring channel. The device further includes a measuring element situated in the measuring channel for determining the at least one parameter. Between its intake and its outlet, the measuring channel features at least one channel segment in which a mechanism is located that causes flow vortices in this channel segment, whereby liquid droplets and solid particles are advantageously deposited on the inner wall of the channel before they can reach the measuring element.