Two laser spectral hole burning in the hyperfine lines of the 646.9 nm transition of 0.0018% Ho 3+:LaCl 3 is presented and discussed. It is shown that the hole burning in this centre can be described by a simple rate equation model where the optical pumping competes with electron-electron and nuclear-nuclear spin flips. We also illustrate using the rate equation model the temporal development of the holes and antiholes and finally present values for the ground state hyperfine and quadrupole interaction strengths, obtained from optical/microwave double resonance measurements.