The grass-cutting head (101) has a body (103) forming a housing for at least one spool of cutting line (F1 F2), provided with at least one outlet hole (111) of an end of the cutting line wound ON said spool positioned inside the head. For each outlet hole, a guide channel for the cutting line is also provided, extending from the inside of the housing towards the hole and having an inclined trend and gradually moving away from said axis of rotation.
