  We discuss nuclear structure functions in lepton scattering including
neutrino reactions. First, the determination of nuclear parton distribution
functions is explained by using the data of electron and muon deep inelastic
scattering and those of Drell-Yan processes. Second, NuTeV sin^2 theta_W
anomaly is discussed by focusing on nuclear corrections in the iron target.
Third, we show that the HERMES effect, which indicates nuclear modification of
the longitudinal-transverse structure function ratio, should exist at large x
with small Q^2 in spite of recent experimental denials at small x.
