  We suggest a new mechanism for naturally suppressing dimension five baryon
number violating in supersymmetric SU(5+N) (N=0, 1,...) GUTs. The mechanism is
realized through suppression of qqT type couplings, and is implemented by
introducing new `matter' multiplets belonging to symmetric representations of
SU(5+N). Together with the suppression of nucleon decay, these multiplets also
enable one to avoid the unwanted asymptotic mass relations $m_s=m_{\mu}$,
$\frac{m_d}{m_s}=\frac{m_e}{m_{\mu}}$.
  As an example, we consider a SU(6) model with pseudo-Goldstone Higgs. By
supplementing the model with an anomalous ${\cal U}(1)$ flavor symmetry, we
also obtain a simple `all-order' solution of the gauge hierarchy problem and
natural explanation of charged fermion mass hierarchies and values of the CKM
matrix elements. The proton life time $\tau_p\sim 10^{2}\tau_p^{SU(5)}$~yr. is
compatible with experiments, with the dominant decay being $p\to K\nu_{\mu,
\tau}$. Thanks to the SU(6) symmetry, successful unification of the gauge
couplings can be retained, and the value of the strong coupling $\alpha_s(M_Z)$
can be reduced to $\simeq 0.12$.
  Finally, we show how to accommodate the solar and atmospheric neutrino data
through the bi-maximal neutrino mixing scenario, with maximal vacuum
$\nu_e-\nu_{\mu, \tau}$ and large angle $\nu_{\mu}-\nu_{\tau}$ oscillations.
