Search for rare purely leptonic decays at LHCb

Rare lepton decays of the B(s), D and K mesons are sensitive probes of New Physics. In particular, the search for the decays $B^0_(s) -> \mu^+ \mu^-$ provides information on the presence of new (pseudo-)scalar particles. LHCb is well suited for these analyses due to its large acceptance and trigger efficiency, as well as its excellent invariant mass resolution and lepton identification capabilities. The status of these analyses with $\sim1$ fb$^{-1}$ of pp collisions collected by LHCb in 2011 at $\sqrt{s}=7$ TeV is reviewed.