The expected experimental sensitivity to the heavy neutral Higgs boson decays H/A → μ μ and H/A → τ μ at the LHC is discussed in the framework of the MSSM and of two type-III Two-Higgs-Doublet Models allowing for lepton flavour violation (LFV), respectively. Despite a small branching fraction, the H/A → μ μ decay allows for a precise measurement of the Higgs boson mass and for an evaluation of the ratio of the vacuum expectation values of the two Higgs doublets, \documentclass[12pt]{minimal}
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\begin{document}$\rm{\tan{\beta}}$\end{document}. The search for the lepton flavour violating decay H/A → τ μ allows stringent constraints to be set on the LFV coupling parameter λτ μ.