  Taking into account uncertainties related with the initial coupling constants
and threshold corrections at low and high scales we find that in standard
supersymmetric SU(5) model the supersymmetry breaking scale could be up to
$10^8$ GeV. In the extensions of the standard supersymmetric SU(5) model the
supersymmetry breaking scale could be up to $O(10^{12})$ GeV.
  In standard SU(5) supersymmetric model it is possible to increase the GUT
scale up to $5 \cdot 10^{17}$ GeV provided that the masses of chiral
superoctets and supertriplets are $m_{3,8} \sim O(10^{13})$ GeV. For SU(5)
supersymmetric model with $10^6$ GeV $\leq M_{SUSY} \leq 10^8$ GeV the Higgs
boson mass is predicted to be 120 GeV $\leq m_h \leq $ 150 GeV.
