Malrieu (2004) approaches genres from a global characterization of them followed by a morphosyntactic and semantic disambiguation of smaller units than the text but bigger units than the sentence. Our study will consist on taking the so-called “buoys” as morphosyntactic element, and see if they are pertinent devices to distinguish between genres in French Belgian Sign Language (LSFB). Buoys are signs produced with the weak hand maintained while the other goes on signing (Liddell, 2003). We have gathered a balanced corpus of one signer including argumentative, explicative, narrative and metalinguistic productions, which has been annotated and analysed. We look at (i) the distribution of buoys across genres and their frequency of appearance; and (ii) the scope of the discourse which is organized by a particular buoy and what the role of the buoy is for discourse cohesion.