  We study the finite-temperature effective potential of the Minimal
Supersymmetric Standard Model in the full (mA, tan(beta)) parameter space. As
for the features of the electroweak phase transition, we identify two possible
sources of significant differences with respect to the Standard Model: a stop
sector with little supersymmetry breaking makes the phase transition more
strongly first-order, whereas a light CP-odd neutral boson weakens its
first-order nature. After including the leading plasma effects, T=0 radiative
corrections due to top and stop loops, and the most important experimental
constraints, we find that the danger of washing out any baryon asymmetry
created at the electroweak scale is in general no less than in the Standard
Model.
