Anisotropies in the cosmic microwave background radiation due to gravi
ty waves are investigated. An initial spectrum of gravity waves may ha
ve been induced during an epoch of inflation. We study the propagation
of such a spectrum in different Friedmann backgrounds with hot and co
ld dark matter, radiation and, possibly, a cosmological constant. We c
alculate its imprint as anisotropies on the cosmic microwave backgroun
d. We also take into account that massless particles can source gravit
y waves by their anisotropic stresses. We consider general mixed dark
matter models with and without cosmological constant. For a given, sca
le invariant input spectrum of gravity waves, we determine the depende
nce of the resulting spectrum of CMB anisotropies on the different par
ameters of the model.