  I describe recent work with V. Cirigliano and E. Golowich on the effect of
dimension eight operators on weak nonleptonic amplitudes. The basic message is
that there is an inconsistency in the way that many calculations are
traditionally performed. If one calculates matrix elements involving only
physics below some scale \mu, then one needs dimension eight operators
explicitly in the weak OPE. On the other hand if one wants to use dimensional
regularization throughout, then one needs all scales to be included within the
matrix element, and this results in the same net effect. A numerical estimate
indicates that this is important below \mu= 2 GeV, and this calls into question
many of the models that have been used to predict \epsilon'/\epsilon.
