The role of prosody and syntax in identifying basic discourse units is a recurring issue in the studies of spoken language. In this paper, we focus on the terminal units of both syntac- tic and prosodic structures, studying respectively illocutionary units and intonative periods. This study focuses on their inter- actions and more specifically on both the synchronization and the relative number of their boundaries. Based on the analy- sis of a large spoken french corpus, we identify different types of such synchronizations (total, partial or absent) and relative proportions. We interpret these results from a functional point of view as an interaction between intono-syntax and the genre of discourse. Remarkably, evidence strongly suggests a much more complex intercation between syntax and prosody than ex- pected under intuitive assumptions. Hence, we believe that the features we propose may be interesting for the study of spoken discourse