When intonation in French is analysed in terms of a multi-dimentional and hierarchical structure, each of the prosodic units such as accent phrases(having different combinations of the basic tonemes L and H), pre-sentencial and post-sentencial long pauses, intonation phrases(containing boundary intonation), as well as intermediate phrases can be considered being realized on a separate tier. Unlike on the tiers where accent phrases and intonation phrases occur, an intonation rhythm consisting of plateaus is realised on that of intermediate phrases. This intonation rhythm consisting of plateaus is one of the significant factors that lead a basic French metrical rhythm. This paper first shows the types of combinations of the basic tonemes L and H found in French accent phrases. Secondly, this paper examines the roles intermediate phrases and plateaus play in French. Finally, this paper argues that intermediate phrases are the metrical units actually adopted as real utterance units in French.