Do electroweak precision data and Higgs-mass constraints rule out a scalarbottom quark with mass of order 5 GeV?

We study the implications of a scalar bottom quark, with a mass of O (5 GeV ), within the minimal supersymmetric standard model. Light sbottoms may nat urally appear for large tan beta and, depending on the decay modes, may hav e escaped experimental detection. We show that a light sbottom cannot be ru led out by electroweak precision data and the bound on the lightest CP-even Higgs-boson mass. We infer that a light (b) over tilde scenario requires a relatively light scalar top quark whose mass is typically about the top-qu ark mass. In this scenario the lightest Higgs boson decays predominantly in to (b) over tilde pairs and obeys the mass bound mh m(h) less than or simil ar to 123 GeV.