Abstract: An apparatus (1) for separating a liquid component from the exhalation gas of a patient to be delivered to one or more analyzing units (3, 4). The apparatus comprises a first chamber (10) for receiving therein an exhalation gas coming from a patient and in which the inflowing gas divides into two components in a manner that some of the gas flows to an analyzing unit and some of the gas, as well as a liquid component possibly entrapped in the exhalation gas, is conducted out past the analyzing unit, a second chamber (12), through which a patient's exhalation gas flows from the first chamber to an analyzing unit, and a gas-permeable wall (11), which separates these chambers and through which the gas flows from the first chamber into the second chamber. Upstream of the wall (11) there is a filter (20), the exhalation gas of a patient flowing through this filter prior penetrating through the wall (11) and the filter (20) allowing therethrough the flow of a liquid component possibly entrapped in the gas.