  We discuss supersymmetric contributions to the electroweak precision
measurements in the Minimal Supersymmetric Standard Model for two cases: the
quark-lepton universality violation $\delta_{q\ell}$ in charged currents and
the ratio $R_b=\Gamma(Z\rightarrow b\bar{b})/\Gamma(Z\rightarrow \rm hadrons)$.
The recent experimental data suggest deviations from the Standard Model for
these observables, at the 1-$\sigma$ level for the former and at more than
3-$\sigma$ level for the latter. We analyze the non-oblique corrections from
the SUSY particles to explain these discrepancies. The observed non-zero
$\delta_{q\ell}$ may be explained by relatively light sleptons, charginos and
neutralinos. Although the observed excess of $R_b$ can be explained by very
light scalar top and chargino for low $\tan\beta$, this interpretation is
severely constrained by the opening of exotic decay modes for the top quark.
