A comparison between theoretical and experimental values for L-subshell ionization cross sections by low-energy protons and alpha particles has been made graphically. The theoretical values are calculated by the relativistic plane-wave Born approximation, including the corrections for the binding-energy and Coulomb-deflection effects. The experimental data are expressed as a ratio to the calculated values and plotted against a reduced velocity parameter. It is found that agreement between theory and experiment is not so good as in the case of the K-shell ionization cross sections. For L//1 and L//3 shell, most experimental data are in agreement with the calculated values within errors of 60%.