The rate of neutron absorption in several gold and copper samples has been measured in the PCTR for two different configurations of the fuel and moderator. From these rates, and the corresponding cadmium ratios, the ratio of copper to gold absorption rates for thermal neutrons, and therefore the ratio of the thermal-neutron absorption cross section of copper to that of gold, has been determined. For a value of σAU (0.0253 ev) = 98.8 ± 0.3 barns, the result σCu (0.0253 ev) = 3.79 ± 0.04 barns is obtained.