Oscillations in both ferromagnetic and antiferromagnetic indirect exchange coupling through Ru are directly measured. Ferromagnetic coupling is determined by spin engineering multilayered structures comprised of trilayers of Ni80Co20/Ru/Ni80Co20 in which one of the Ni80Co20 layers is strongly antiferromagnetically pinned to a Co layer. Oscillations in antiferromagnetic exchange coupling are measured in companion Ni80Cu20/Ru multilayers. The dependence of the exchange coupling strength on Ru thickness is well described by the Ruderman-Kittel-Kasuya-Yosida far-field range function, providing a direct measurement of this function through a transition metal. © 1991 The American Physical Society.