  The effects of reionization, occurring after standard recombination in cold
dark matter-dominated models, on CMB anisotropies are investigated. Late-time
reionization reduces the CMB anisotropies, in particular, on degree scales. It
is found that constraints on cold dark matter-dominated models from the highest
frequency channel of the 9-point South Pole data are significantly relaxed for
models which are consistent with Big Bang nucleosynthesis if reionization is
assumed to have occurred by redshift $\sim 20.$
