During 23 months period, entomological surveys were carried out in three villages of a mangrove area and two others far of the mangrove in the south part of Senegal. An. gambiae s.s was the main malaria vector and the sampling of its population was done by human baits catch. The An. gambiae density was important in the rainy season and the malaria transmission occurred from July to November; the inoculation rate rose from 0 to 123 infected bites per man. Marked yearly and local variations of the transmission intensity were observed. The transmission intensity was higher in the villages far of the mangrove than in those near. The variations of the transmission intensity were related to the larval breeding sites and to the longevity of the An. gambiae females.