  Various BSM models predict large deviations of the top electroweak couplings.
Many examples will be given emphasizing the need for precise and model
independent measurements of these couplings. Here I address the question of
compatibility between theoretical predictions and the LEP/SLC/Tevatron
constraints which, through loop effects, allow setting very significant
constraints on these predictions. A Randall Sundrum inspired prediction will be
discussed in more details. Finally the prospects offered by LHC and ILC
measurements for top EW couplings are briefly reviewed.
