Abstract Due to the evolution of the band structure through the series, the rare earth R-3d metal compounds form outstanding tools for the study of the 3d and/or 4f magnetic instabilities. Such instabilities are illustrated in this paper for three types of systems: i) the Y-Ni system with a special emphasis on the “thermal spontaneous magnetization” observed in Y 2 Ni 7 , ii) the R-Co system where “collective electron metamagnetism” and Co antiferromagnetism are observed in the RCo 2 (as in ThCo 5 ), and in La 2 Co 1.7 and La 2 Co 3 , respectively; iii) the Ce-Ni system where the 4f instability is quite characteristic in the CeNi intermediate valence compound in which large magnetovolume effects were determined.