The radiation damage in molybdenum produced by 14 MeV neutrons has been compared with that produced by fission reactor neutrons. The increased damage level from 14 MeV neutrons compared to fission neutrons as measured by lattice parameter and microstructural changes is much greater than predicted from displaced atom calculations. The damage level measured by electrical resistance changes nearly agrees with the displaced atom calculations. The results are interpreted in terms of an increase in the ratio of clustered defects to free defects after 14 MeV neutron irradiation compared to fission reactor irradiations.