In a cigarette packeting machine, the formation of groups of cigarettes to be packeted disposed in superposed layers of which at least one is incomplete in that it lacks at least one intermediate cigarette. The cigarettes of the incomplete layer being kept in position, inside a formation and advancement pocket for the relative group, by the cigarettes of an immediately upper complete layer which are fed into the pocket so that they become disposed quincuncially to the cigarettes of the incomplete layer.