A head for brush cutters wherein a rotary shell comprising a lower annular body and an upper cover is slidingly coupled with a feeding assembly which comprises a sprocket and a base cap, co-operating with each other by way of rotatory motion transmission means, preferably of a unidirectional type, which engage to each other thanks to the action exerted by elastic contrast means, the latter interposed between the cover of the rotary shell and the sprocket of the feeding assembly.