  In the framework of the quasipotential method in quantum electrodynamics we
calculate the contribution of pseudoscalar mesons to the interaction operator
of a muon and a proton in muonic hydrogen atom. The parametrization of the
transition form factor of two photons into $\pi$, $\eta$ mesons, based on the
experimental data on the transition form factors and QCD asymptotics is used.
Numerical estimates of the contributions to the hyperfine structure of the
spectrum of the S and P levels are presented.
