  The D^0-D^0(bar) mixing is analyzed in a weak gauged U(4)_L x U(4)_R chiral
lagrangian model where the electroweak interaction is introduced as a gauge
theory over the meson degrees of freedom. This model allows a particular
realization of the G.I.M. mechanism and then could be useful in the study of
processes where G.I.M. suppression is effective. As a test of the model we have
also analyzed the K^0-K^0(bar) mixing. We find \Delta m_K in good agreement
with the experimental result and we show that the D^0-D^0(bar) mixing is very
much suppressed in agreement with previous estimates in the Heavy Quark
expansion framework.
