Star forming regions are one of the active components of the interstellar medium and as such play an important role in the galactic “ecosystem”. When massive young stars are borned they have a strong impact on their environment through their radiation flux and stellar wind. We are then facing complicated interplays between gas in different states (ionized, atomic and molecular), dust particles and the young stars. The understanding of these interplays can only be done using multifrequency observations. Such an endaveour is already in progress (see Joncas et al. 1988 and Kömpe et al. 1989). We will describe here the young star forming region S187 (Sharpless 1959). This gas complex is nearby (≈1 kpc) thus permitting high spatial resolution with medium size instruments. It contains a faint optically visible HII region ionized by an unidentified BO or BO.5 star. The associated molecular cloud, discovered by Blair et al. (1975), contains a molecular outflow (Bally and Lada 1983) to which an H2O maser is associated (Henkel et al. 1986).