In this lectures we review the main idea of the chiral doublers scenario, originating from simultaneous constraints of chiral symmetry and of heavy quark spin symmetry on effective theories of heavy--light hadrons. We discuss chiral doublers for mesons and (briefly) chiral doublers for baryons in light of recent experimental data.

PACS numbers: 12.39.Dc, 12.39.Hg, 14.20.Lq, 14.40.Lb