This paper presents the results of ventilation measurements taken in a non-occupied one-storey dwelling situated in the countryside. The measurements of the ventilation rates in the different rooms have been obtained by the use of tracer gases with the constant concentration technique. Four configurations of ventilation systems have been tested successively. The ventilation systems tested consist of natural air supply and mechanical exhaust. Both 'normal' air supply grilles and self-regulating grilles have been tested. The exhaust system installed is a mechanical system without regulation.""""The results show the importance of the ventilation in dwellings, the selection and dimensioning of effective ventilation devices as well as the correct use of the equipment installed.