  We review investigations of the electron-phonon interaction (EPI) in metal
diborides MeB_2 (Me=Zr, Nb, Ta, Mg) by point-contact (PC) spectroscopy. For
transition metal compounds the PC EPI functions were recovered and EPI
parameter $\lambda\lesssim 0.1$ were estimated. The data are consistent with
the measured surface phonon dispersion curves. The low $\lambda$ value
questions some reports about superconductivity in these compounds. Contrary,
EPI in superconducting MgB_2 films manifests also in the PC spectra itself by
virtue of an elastic EPI contribution to the excess current determined by the
energy dependence of the superconducting order parameter. To analyse the phonon
features in the PC spectra of MgB$_2$ a two-band model is exploited and the
proximity effect in the {\bf k}-space is suggested.
