  In a simple hadronic model, the two-photon exchange contributions to the
single spin asymmetries for the nucleon and the $^3$He are estimated. The
results show that the elastic contributions of two-photon exchange to the the
single spin asymmetries for the nucleon are rather small while those for the
$^3$He are relatively large. Besides the strong angular dependence, the
two-photon contributions to the single spin asymmetry for the $^3$He are very
sensitive to the momentum transfer.
