Physics at LEP and Yukawa coupling unification

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.