  We use the recent CMB power spectrum measurement by the Maxima experiment
(Hanany et al. 2000) to constrain the redshift of reionization z_re. This
becomes possible by combining the CMB data with cosmological parameters from
various independent measurements, including Big Bang Nucleosynthesis (BBN) and
X-ray cluster data. Most notably, our results provide a robust lower bound on
z_re. We find that z_re>15 (8) at the 68% (95%) confidence level, unless the
Hubble constant is larger than 75 km/s/Mpc.
