Mg II emissions in the IUE spectra of 91 cool stars are analyzed in a systematic search for interstellar components. About 60 percent of the stars show evidence of interstellar contamination. The radial velocities of the features show that even at short distances (d less than 30 pc) the motion of the local interstellar medium (LISM) agrees with that derived from the analysis of optical absorptions in the directions of more distant stars (Crutcher, 1982). The absence of detectable interstellar lines has made it possible to derive stringent upper limits along the line of sight of many stars. The results suggest that the density of the gas in the immediate vicinity of the sun may be lower than previously estimated. In particular, the presence of the low-density region towards the northern galactic pole around HZ43 is confirmed.