  In the framework of the four dimensional heterotic superstring with free
fermions we present a revised version of the rank eight Grand Unified String
Theories (GUST) which contain the $SU(3)_H$-gauge family symmetry. We also
develop some methods for building of corresponding string models. We explicitly
construct GUST with gauge symmetry $ G = SU(5) \times U(1)\times (SU(3) \times
U(1))_H$ and $G = SO(10)\times (SU(3) \times U(1))_H $ or $E(6)\times SU(3)_H$
$\subset E(8)$ and consider the full massless spectrum for our string models.
We consider for the observable gauge symmetry the diagonal subgroup $G^{symm}$
of the rank 16 group $G \times G$ $\subset SO(16) \times SO(16)$ or $\subset
E(8) \times E(8)$. We discuss the possible fermion matter and Higgs sectors in
these theories. We study renormalizable and nonrenormolizable contributions to
the superpotential. There has to exist "superweak" light chiral matter ($m_H^f
< M_W$) in GUST under consideration. The understanding of quark and lepton mass
spectra and family mixing leaves a possibility for the existence of an
unusually low mass breaking scale of the $SU(3)_H$ family gauge symmetry (some
TeV).

High Energy Physics - Phenomenology