Summary.The translocation of14C‐labelled herbieides in field bracken has been sludied in some preliminary experiments by means of autoradiography. A detailed account is given of the methods employed. It is shown that when 2,4‐D is applied to fronds at different stages of development movement of the tracer into the rhizome is considerably greater from parts of the frond which are still immature. Trasnslocation within the frond is predominantly basipetal at all stages of development; within the rhizome the direction of movement appears to be determined primarily by the nature of the vascular connections with the treated pinna.In a comparison between the translocation of 2,4‐D, 4‐CPA and dalapon no difference was apparent after 24 hours, but when the treatment period was extended to 96 hours there was evidence that 4‐CPA bad been translocated in a considerably greater amount than either of the other two herbicides.Rechrches iréliminaires sur la migration des herbieides marqués am14C dans la fougrère algle(Pteridi