  During the recombination epoch, cosmic background photons couple not only to
free electrons through Thompson scattering, but also to the neutral hydrogen
through Rayleigh scattering. This latter is ~2% effect for photons near the
peak of the photon energy distribution at z=800 and a ~0.2% effect at z=1100.
Including Rayleigh scattering in the calculation reduces Silk damping at fixed
redshift, alters the position of the surface of last scattering and alters the
propagation of acoustic waves. We estimate the amplitude of these effects. For
the Microwave Anisotropy Probe (MAP), Rayleigh scattering increases the
anisotropy spectrum by 0.1% at the most. For the highest frequencies of the
Planck Surveyor, the effects of Rayleigh scattering are much more dramatic
(decreasing the anisotropy spectrum by 3% at \nu~550GHz and l~1000). The
relative difference between the spectra of low and high frequencies is imposed
by an oscillation with a function of multipole l and the oscillation amplitude
is up to 0.5% between 100 and 550GHz. Rayleigh scattering also slows the
decoupling between radiation and matter, but the effect is undetectably small.
