A method of folding a sheet of packing material, having an extraction opening, about a group of cigarettes; the method includes the steps of: bringing a first end wall of the group of cigarettes into contact with the flat sheet of packing material, so that the major transverse edges of the group of cigarettes are parallel to the short sides of the sheet of packing material, and the minor transverse edges of the group of cigarettes are parallel to the long sides of the sheet of packing material; folding the sheet of packing material into a U about the major transverse edges of the first end wall, so that the sheet of packing material covers both the major lateral walls of the group of cigarettes completely; folding the sheet of packing material onto a second end wall of the group of cigarettes; and folding the sheet of packing material onto the minor lateral walls of the group of cigarettes; the first end wall of the group of cigarettes is positioned asymmetrically with respect to the sheet of packing material, so that the first end wall of the group of cigarettes is closer to the short side of the sheet of packing material opposite the extraction opening, and is further from the short side of the sheet of packing material located close to the extraction opening.