  We review the loop effects of the low energy supersymmetry. The global
success of the Standard Model rises two related questions: how strongly the
mass scales of the superpartners are constrained and can they be, nevertheless,
indirectly seen in precision measurements. The bulk of the electroweak data is
well screened from supersymmetric loop effects, due to the structure of the
theory, even with superpartners generically light, $O(M_Z)$. The only exception
are the left-handed squarks of the third generation which have to be $\simgt
O(300$ GeV) to maintain the success of the SM. The other superpartners can
still be light, at their present experimental mass limits, and would manifest
themselves through virtual corrections to the small number of observables such
as $R_b, b \to s\gamma, K^0-\bar K^0$ and $B^0-\bar B^0$ mixing and a few more
for large $tan\beta$. Those effects require still higher experimental precision
to be detectable.
