I discuss low energy aspects of heavy meson decays, where there is at least one heavy meson in the final state. Examples are B--\overline {B} mixing, B \rightarrow D \overline {D}, B \rightarrow D \eta ', and B \rightarrow D \gamma . The analysis is performed in the heavy quark limit within heavy--light chiral perturbation theory. Coefficients of 1/N_c suppressed chiral Lagrangian terms (beyond factorization) have been estimated by means of a heavy--light chiral quark model.

PACS numbers: 13.20.Hw, 12.39.St, 12.39.Fe, 12.39.Hg