  We explore direct collider probes of the resonant leptogenesis mechanism for
the origin of matter. We work in the context of theories where the Standard
Model is extended to include an additional gauged U(1) symmetry broken at the
TeV scale, and where the light neutrinos obtain mass through a Type I seesaw at
this scale. The CP asymmetry that generates the observed matter-antimatter
asymmetry manifests itself in a difference between the number of positive and
negative like-sign dileptons N(\ell^+\ell^+)-N(\ell^-\ell^-) that arise in the
decay of the new Z' gauge boson to two right-handed neutrinos N, and their
subsequent decay to leptons. The relatively low efficiency of resonant
leptogenesis in this class of models implies that the CP asymmetry, \epsilon,
is required to be sizable, i.e. of order one. In particular, from the sign of
the baryon asymmetry of the Universe, \emph{an excess of antileptons is
predicted}. We identify the domains in M_{Z'}--M_N space where such a direct
test is possible and find that with 300~fb^{-1} of data and no excess found,
the LHC can set the $2\sigma$ exclusion limit \epsilon \lesssim 0.22.
