The Mg II chromospheric emissions in cool stars were analyzed using high resolution IUE archive spectra. The ways in which interstellar (IS) absorptions can affect the shapes of the chromospheric profiles are discussed. It is possible to indicate regions of the sky where the Mg II IS absorption can be neglected, up to distances of a few tens of parsecs. When the absorption is present, radial velocity can be estimated, to predict the kind of distortion introduced onto the line profile. Once the IS contamination is taken into account, the chromospheric profiles of the stars tend to have a homogeneous behavior.