  We discuss the impact of the recent precision measurements at LEP on the
minimal supersymmetric standard model. We show that the values of $\tan\beta$
necessary to induce large positive corrections to $R_b$ are the same as the
ones preferred by the unification of the bottom and $\tau$ Yukawa couplings in
the MSSM for the current measured value of $M_t$. We discuss the relevance of
the preferred parameter space for the Higgs and sparticle searches at LEP2.
Remarkably, it follows that the LEP measurements can provide information about
the structure of soft supersymmetry breaking parameters at $M_{GUT}$. Finally,
we briefly discuss the properties of a supersymmetric model with four
generations, for which the fit to $R_b$ naturally improves with respect to the
one in the Standard Model.
