  We reexamine the constraints on universal extra dimensional models arising
from the inclusive radiative Bbar -> X_s gamma decay. We take into account the
leading order contributions due to the exchange of Kaluza-Klein modes as well
as the available next-to-next-to-leading order corrections to the Bbar -> X_s
gamma branching ratio in the standard model. For the case of one large flat
universal extra dimension, we obtain a lower bound on the inverse
compactification radius 1/R > 600 GeV at 95% confidence level that is
independent of the Higgs mass.
