The 233, 234, 236, 238U fission cross sections have been measured relative to 235U(n, f) for incident neutron energies from 200 KeV to 200 MeV using neutron time-of-flight at the Los Alamos Neutron Science Center. The results are generally consistent with the current ENDF/B-VII evaluation, but some discrepancies with previous measurements above 20 to 30 MeV are observed. These measurements are part of a campaign to measure fission cross sections with high precision in support of fast reactor technology.