The author describes the recent changes of rules and proceedings in the House of Representatives, later on in the Senate and finally in both the new «cultural Assemblees», concerning the existence, the functioning and the importance of parliamentary groups and their leaders. Assimilated to the status of Vice-presidents of their Assembly, the parliamentary leaders are in charge of many responsabilities and more attention is given to the parliamentary group as such rather than to the individual members. Seating the members in the House, allocating to their «mandated» members speaking time in important debates, replacing members of their group in the specialized committees, preparing with the Speaker the public debates, taking full responsability for the material aid provided to their group and their members (secretarial help, technical assistance in the committee stage and money supply for research) the many tasks of the parliamentary leaders in the organization of parliamentary work are increasing. Their political functions are much more important. Usually the parliamentary leader sits in the top policy making organs of his party, very often he has had governmental experience and, as a floor leader, intervenes in the important debates. Even if essential differences can be observed between political parties (more freedom of action for the liberals and christian-democrats as a parliamentary group, less for the socialists and the communists) the leader in the Parliament plays an important role as the link between political parties and parliament.