  We study the radiative spontaneous electroweak symmetry breaking in the extra
dimensions scenarios of the standard model extension proposed by Antoniadis
{\it et al}, Dienes {\it et al.} and Pomarol {\it et al.}. In the framework of
multi-scale effective theory when viewing from the ultraviolet cutoff scale
down to the low energy scale, we find that the effects of Kaluza-Klein
excitations of bosons can change the sign of the Higgs mass term of the
standard model from positive to negative and therefore trigger the electroweak
symmetry breaking at 1.6 (2) TeV or so when the compactification scale is
assumed to be 0.8 (1.5) TeV or so. New particle contents beyond the SM or
supersymmetry are not necessary for this mechanism. We conclude that in the
extra dimension scenarios, the radiative correction can naturally induce the
desired electroweak symmetry breaking.
