The present study was designed to assess the health risk of the future hydroelectric dam of Memve'ele with reference to vector-borne diseases. Entomological and malacological surveys were carried out in the project area. The main vectors collected were Anopheles gambiae and An. nili for malaria; Simulium damnosum for onchocerciasis; Glossina palpalis for trypanosomiasis; Chrysops dimidiata and C. silacea for loasis. No snail host of schistosome was reported. The risk of introduction of the diseases they transmit are discussed.