A unit for grouping packages along a transfer path includes an input station receiving the packages arranged in longitudinal lines parallel to the transfer path; an output station for groups defined by a given number of packages from respective longitudinal lines and aligned in at least one line crosswise to the transfer path. A movable conveying surface is supplied at predetermined time intervals with a number of packages equal to that in each group, and which feeds the packages along the transfer path. At least one aligning member is moved cyclically along a first path having a work portion parallel to the transfer path, and at least one push member is moved cyclically along a second path having a work portion parallel to the transfer path. The aligning member and the push member are moved respectively by independent first and second conveying mechanisms.