  Using an effective interaction approach to describe the interactions between
the dark matter particle and the light degrees of freedom of the standard
model, we calculate the antiproton flux due to the annihilation of the dark
matter in the Galactic Halo and compare to the most recent antiproton spectrum
of the PAMELA experiment. We obtain useful constraints on the size of the
effective interactions that are comparable to those deduced from collider and
gamma-ray experiments.
