  We consider propagation of heavy quarks in QCD matter. Because of large quark
mass, the radiative quark energy loss appears to be qualitatively different
from that of light quarks at all energies of practical importance. Finite quark
mass effects lead to an in-medium enhancement of the heavy-to-light D/\pi ratio
at moderately large (5--10 GeV) transverse momenta. For hot QCD matter a large
enhancement is expected, whose magnitude and shape are exponentially sensitive
to the density of colour charges in the medium.
