In the minimal supersymmetric model (MSSM), the upper limit of the lightest
Higgs boson mass, \mhl, depends strongly on the top quark mass, mt. We
have computed the dominant two-loop radiative corrections to this upper limit
of \mhl in order to eliminate large uncertainties due to QCD and mt6
corrections. It is shown that the QCD corrections significantly reduce the
one-loop corrections. As a result, the SUSY parameter space accessible to LEP
experiments is significantly increased.Comment: 14 pages using PHYZZX, 4 figs. are appended as PS-file