The relation between the constitutionally founded supremacy of the parliament and the authoriy of the Prime Minister (PM) based on common law, is of a great importance in the Low Countries. This relation constitutes the difference between parliamentary and presidential regimes. It is the PM's duty to take care of the permanent support ofthe parliamentary majority. This is not an easy exercise. Members of parliament are not always as positive about the PM's parliamentary performances. Characteristics of the parliamentary activity of the Belgian PM's Wilfried Martens, Jean-Luc Dehaene and the Dutch Ruud Lubbers are handled as: the frequency and the extent of the PM's parliamentary performances, the topics handled by the PM's in parliament, the PM's opponents in parliamentary debate and finally more generally the PM's parliamentary role behaviour. Due to the different position of both the parliament and the PM in the Belgian and the Dutch political system, the characteristics of the parliamenty activity of the Belgian and the Dutch PM are not always very similar. Additionally, remarkable differences occur between the parliamentary activity of different PM'swithin the same country.