  The regularization scheme dependence of running couplings in extra
compactified dimensions is discussed. We examine several regularization schemes
explicitly in order to analyze the scheme dependence of the Kaluza-Klein
threshold effects, which cause the power law running, in the case of the scalar
theory in five dimensions with one dimension compactified. It is found that in
1-loop order, the net difference in the running of the coupling among the
different schemes is reduced to be rather small after finite renormalization.
An additional comment concerns the running couplings in the warped extra
dimensions which are found to be regularization dependent above TeV scale.
