  We study the IR/UV connection in non-commutative $\phi^{3}$ theory as well as
in non-commutative QED from the point of view of the dispersion relation for
the self-energy. We show that, although the imaginary part of the self-energy
is well behaved as the parameter of non-commutativity vanishes, the real part
becomes divergent as a consequence of the high energy behavior of the
dispersion integral. Some other interesting features that arise from this
analysis are also briefly discussed.
