Studies the problem of quantizing the gravitational field in interaction with scalar mesons when gravity has certain non-minimal terms in addition to Einstein's Lagrangian. The extra poles in the graviton propagator are described and the authors attempt to remove the ghost particle in lowest-order graphs. It is that this is not possible, and a 2-meson-1-graviton scattering graph is considered whose S-matrix contribution has a ghost pole at the 2-meson threshold. If graviton ghost cancellation were possible the usual renormalizability criterion is required to prevent meson ghost appearances.