  Heavy squark decays into top and charginos or neutralinos could be an
unexpected source of top quarks at hadron colliders. A detailed treatment of
these processes is necessary for a reliable calculation of both the top quark
production cross-section and the standard top quark branching ratio in the
MSSM. Along this line we compute the electroweak corrections to the sbottom
decays sbottom_a --> chargino_i top within the Yukawa coupling approximation.
The calculation of these higher order contributions requires renormalization of
both the bottom squark mixing angle and of tan(beta). This type of corrections
gives the leading order electroweak effects at low and high tan(beta).
