The neutron capture cross section of 243Am was measured from 258 eV to 92 keV. The relative capture cross sections were normalized to 74.8 b at 0.0253 eV from ENDF/B-V. Agreement with the one previous measurement in the kilo-electron-volt neutron energy range is reasonably good (∼8%). These results are needed for calculating the buildup of higher actinides in operating reactors.