During and after a Rift Valley fever (RVF) epidemic in Southern Mauritania we collected 600 clinical observations. 348 were confirmed to be RVF cases. We described 5 major clinical aspects: mild, icteric, icterohemorrhagic, hemorrhagic and neurological forms. The first one is the most frequently seen with 42.8% of the cases at admission. Fever was associated with various pains (cephalalgia, myalgia, arthralgia) and an important asthenia. Inconsistently this syndrome was accompanied by epistaxis and conjunctival hyperemia. The icteric form, never described before, is an icterus occurring during evolution of a mild form. It represents 28.5% of total cases at admission. The great number of theses mild forms implies that they could be used as excellent markers for an epidemic emergence.