  An alternative supersymmetric SO(10) grand unification model with lopsided
fermion mass matrices is introduced. It generates a large solar-neutrino-mixing
angle through the neutrinos' Dirac mass matrix constrained by the SO(10) group
structure, avoiding the fine-tuning required in the Majorana mass matrix of
right-handed neutrinos. The model fits well the known data on masses and
mixings of quarks and leptons, and predicts a sizable lepton mixing
$\sin^22\theta_{13}\simeq 0.074$, which is significantly larger than that of
the original lopsided model.
