The magnetic properties of the cubic RCu5compounds TbCu5, DyCu5, HoCu5, ErCu5, and TmCu5are reported for temperatures between 2.1° and 300°K. In the paramagnetic region the susceptibility follows a Curie‐Weiss law. The type of ordering at low temperatures changes with increasing atomic number from antiferromagnetic (R = Tb) to ferromagnetic (R = Ho, Er, Tm), while DyCu5is metamagnetic. The Knight shifts of the63Cu NMR in these compounds have been measured between 100° and 300°K. The results are discussed in terms of the Ruderman‐Kittel‐Kasuya‐Yosida theory.