The role of prosody and syntax in identifying basic discourse units is a recurring issue in the studies of sp oken language. In this pap er, we fo cus on the terminal units of b oth syntactic and proso dic structures, studying resp ectively illo cutionary units and intonative p erio ds. This study fo cuses on their interactions and more specifi cally on both the synchronization and the relative number of their boundaries. Based on the analysis of a large spoken French corpus, we identify di erent typ es of such synchronizations (total, partial or absent) and relative prop or- tions. We interpret these results from a functional point of view as an interaction between intonosyntax and the genre of discourse. Evidence strongly suggests a much more complex interaction between syntax and prosody than expected under intuitive assumptions. Hence, we believe that the features we propose may be interesting for the study of sp oken discourse.