The spectra of circularly polarized luminescence of the paramagnetic garnets Y 3 Al 5 O 12 :Tb 3+ and Y 3 Al 5 O 12 :Ho 3+ in magnetic field have been studied experimentally in the visible range of wavelength for the 5 D 4 → 'F 5 transition of the Tb 3+ ions and for the 5 S 2 → 5 I 8 transition of the Ho 3+ ions. A great difference has been found in the intensities of orthogonal circularly polarized components for a number of luminescence lines. The findings are explained by a mechanism of mixing of electronic states of the Tb 3+ and Ho 3+ ions in the matrix of the Y 3 Al 5 O 12 garnet in an external magnetic field. The results of numerical calculations of the energy spectra of the 7 F 5 multiplet of the Tb 3+ ions in a crystalline field of D 2 symmetry are presented.