Absorption spectra ofYAlO3:Ndfor the three crystallographic axes are investigated at room temperature. The spectral strengths indicate that the absorption coefficient ofYAlO3:Ndis anisotropic. The anisotropy of the local electric field acting on the rare-earth ion in a laser crystal is considered. An extended Judd–Ofelt theory is applied to calculate the absorption cross sections and oscillator strengths of the electric-dipole transitions in the different principal directions. Three groups of the phenomenological parameters are derived from a least-squares-fitting procedure. We also analyze theoretically the anisotropy of the optical absorption ofYAlO3:Ndcrystal in detail. ©1997 American Institute of Physics.