This paper describes high-energy neutron inelastic scattering measurements of propagating magnetic excitations in PrBa2Cu3O6+x (x approximate to 0.2 and 0.93). The measurements probe the acoustic and optic modes of the antiferromagnetically ordered copper-oxygen bilayers in the energy range 50-150 meV. The observed magnon dispersion can be described satisfactorily in this energy range by a spin wave model including intra- and inter-layer nearest-neighbor exchange constants J(parallel to) and J(perpendicular to). We find J(parallel to)=127 +/- 10 meV and J(perpendicular to)=5.5 +/- 0.9 meV. The value of J(parallel to) is virtually the same as that found in YBa2Cu3O6.2, but J(perpendicular to) is a factor of 2 smaller. To within experimental error the values of J(parallel to) and J(perpendicular to) for PrBa2Cu3O6+x, do not vary with oxygen doping.