We have measured the ratio of the 235U fission cross section to the 6Li(n, α) cross section at neutron energies from thermal to 680 keV. The Lawrence Livermore Laboratory electron Linac provided a pulsed source of neutrons, and energies were measured by time-o f-flight. The evaluated 6Li cross section was used to obtain σ(n, f) for 235U from 100 eV to 680 keV and to normalize the results to the accepted thermal fission cross-section value.