$R_b$ in the MSSM: how big can it be?

The possible magnitude of the supersymmetric contribution to Rb with imposed all available phenomenological constraints and demanding good quality of the global fit to the precision electroweak data is summarized. For small tan$\beta$ and $M_{2} \approx |\mu| and \mu < 0$, Rb remains large, ~ 0.2180 even for the lighter chargino mass ~ 90 GeV. It is an interesting mixture of the up-higgsino and gaugino. The large tan $\beta$ option (still not ruled out) for enhancement of Rb is also reviewed. In this case Rb up to ~ 0:2186 can be obtained.