The influence of the target density on the electron‐capture (EC) processes in collisions of fast ions with atoms and molecules is considered. The partial EC cross sections &sgr;non the principal quantum numbernof the scattered projectile, as well as the total &sgr;totvalues are calculated for highly charged ions interacting with gaseous and solid targets in the energy range ofE= 100 keV/amu to 10 MeV/amu. It is shown that with the target density increasing, the population of the excited states of the scattered projectiles, formed via the EC channel, is suppressed due to projectile ionization by the target particles and, as a result, the effective EC cross sections drastically decrease. © 2004 American Institute of Physics