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.