As potential progenitors of the Ap stars, the pre-main sequence intermediate mass Herbig Ae/Be stars present us with the opportunity to investigate theearly history of magnetic fields at these masses. Although we have nodirect evidence for the presence of magnetic fields in thesestars (except in one case), many clues for such fields have been identified in the past years. They include active phenomena which areoften attributed to surface magnetic fields. Rotational modulation ofspectral lines formed at the photosphere and in the wind of these starsconstitutes yet another indication for the presence of such fields. Future prospects for the detection and mapping of hypotheticalmagnetic fields in Herbig Ae/Be stars are very encouraging, andin particular spectropolarimetric observations of these stars withinstruments like Espadons on CFHT will allow us to test thehypothesis that magnetic fields similar to those found on Ap starsare indeed present in these pre-main sequence objects.