Selection-excited spectra and fluorescence lifetimes of Tb3+ and Ce3+ ions in yttrium gallium garnets are obtained at room temperature. In Y3Ga5O12:Tb, Ce, Tb3+ (donor) emission spectrum and Ce3+( acceptor) excitation spectrum overlaps considerably. The observed fluorescence lifetimes of Tb3+ 5D3 and 5D4 levels decrease with Ce3+ concentration when the sample of Y3Ga5O12: Tb, Ce are excited by UV laser pulse. The mechanisms for nonradiative energy transfer from 5D3 and 5D4 states of Tb3+ to 2D3/2 state of Ce3+ are found to be electric dipole-dipole interaction. The critical distance, rate and efficiency of energy transfer from Tb3+ to Ce3+ ion are obtained. The average critical transfer distance (R0) for 5D3 and 5D4(Tb3+)→2D3/2(Ce3+) are 16.3 ? and 11.2 ?, respectively. Although the energy transfer from the 5D4 state is dominated by dipole-dipole interaction, the dipole-quadrupole interaction must also be considered.