The resonant vibronic effect in high-resolution luminescence spectra of europium compounds is investigated. The cases of weak and strong nonadiabatic vibronic mixing between the 7F2-electronic state of Eu3+ and near-resonant vibronic satellites of the 7F0-electronic state are considered. The intensity redistribution and line shifts in the region of the e5D0-7F2 transition are observed. The conditions of resonance disappear in the deuterated compounds when vibration frequencies are appreciably decreased. Creation of new vibronic states is witnessed by emergence of their satellites due to lattice vibrations in vibronic sideband of 5D0-7F2 transition.