  We study the constraints from updated electroweak data on the three
leptophobic Z' models, the ${\eta}$ model with an appropriate $U(1)'-U(1)_Y$
kinetic mixing, a Z' model motivated by the flipped SU(5) \times U(1)
unification, and the phenomenological Z' model of Agashe, Graesser, and
Hinchliffe.
  The $Z-Z'$ mixing effects are parametrized in terms of a positive
contribution to the $T$ parameter, $T_{new}$, and the effective mass mixing
parameter, $\bar{\xi}$. All the theoretical predictions for the $Z$ boson
parameters, the $W$ boson mass and the observables in low-energy neutral
current experiments are presented together with the standard model radiative
corrections. The allowed region in the ($\bar{\xi},T_{new}$) plane is shown for
the three models. The 95% CL lower limit on the heavier mass eigenstate $Z_2$
is given as a function of the effective $Z-Z'$ mixing parameter $\zeta$.
