Neutron-antineutron oscillations in SO(10): Are they really observable?

We investigate the possibility of observable neutron-antineutron oscillations in SO(10). We conclude that, although possible, they require the presence of scalars with masses orders of magnitude away from any physical scale connected with the symmetry breaking. Furthermore, they imply a breaking of left-right symmetry at a mass scale greater than ${10}^9$ GeV and a grand unification mass of order ${10}^{18}$-${10}^{19}$ GeV.