Grouping unit and method to form groups of hygiene absorbent articles in a packaging machine; a conveyor which receives the single hygiene absorbent articles in an input station is provided, which feeds the hygiene absorbent articles along a grouping path, and releases the groups of hygiene absorbent articles in an output station; wherein the conveyor has a belt which is closed so as to form a ring, is wound around at least two pulleys, and supports a plurality of blades, which extend perpendicular to the belt and delimit, between one another, respective pockets, which are each designed to hold a corresponding hygiene absorbent article; an active braking device is provided, which is arranged at the input station so as to cooperate with a pocket arranged in the input station to slow down the movement with which a corresponding hygiene absorbent article enters the pocket.