This study reports for the first time on the distribution, host preference and infection rates of malaria vectors in Mauritania. It was conducted during an outbreak of Rift valley fever. Three anopheline species were reported. An. arabiensis was the predominant species observed in all regions whereas An. pharoensis and An. funestus were observed along the south border in the Senegal River valley where extensive irrigation schemes are present. The distribution limits of anopheline species were observed from the Senegal River basin in the Trarza region up to the south limit of the Saharan desert in Tidjikja city. Overall, all An. funestus and An. pharoensis were fed respectively on human and ovine hosts whereas the mean anthropophilic rate of An. gambiae s.l. was 53%. A low Plasmodium falciparum infection rate was observed for species of the An. gambiae complex (0.17%) represented mainly by An. arabiensis. Because of the specific nature of this investigation, longitudinal studies are essential to better characterize the malaria vectors and their respective role in malaria transmission.