  We discuss renormalization effects on neutrino masses and mixing angles in a
supersymmetric string-inspired SU(4) X SU(2)_L X SU(2)_R X U(1)_X model, with
matter in fundamental and antisymmetric tensor representations and singlet
Higgs fields charged under the anomalous U(1)_X family symmetry. The quark,
lepton and neutrino Yukawa matrices are distinguished by different
Clebsch-Gordan coefficients. The presence of a second U(1)_X breaking singlet
with fractional charge allows a more realistic, hierarchical light neutrino
mass spectrum with bi-large mixing. By numerical investigation we find a region
in the model parameter space where the neutrino mass-squared differences and
mixing angles at low energy are consistent with experimental data.
