A study was conducted to characterize larval habitats of anopheline mosquitoes inrnirrigation and major drainage areas between Adami Tulu and Meki towns, in the middlerncourse of the Ethiopian Reft Valley. A total of 22 anopheline larval positive aquaticrnhabitats were sampled fortnightly from late December 2007 to early June 2008 by usingrndipping techniques. Simultaneously, environmental variables of the larval habitats werernalso measured/estimated and recorded. A total of 3,439 anopheline and 5,213 culicinernlarvae were collected. Microscopic identification of the late instars (3rd and 4th) ofrnanopheline larvae yielded 47.6% of An. pharoensis, 32.1% An. gambiae s.l. larvaern(presumably An. arabiensis) and only 20.3% other anopheline larval species (An.rnsquamosus, An. coustani and An. cinereus). Anopheles larvae were sampledrnpredominantly from natural swamps, irrigation canals and sand pools with samples fromrnthese habitat types representing 88.0% (3025) of the total anopheline larval collection inrnthe study area. Larvae of the malaria vector species, An. gambiae s.l. (An. arabiensis) andrnAn. pharoensis were most frequently sampled from sand pools and natural swamps,rnrespectively. The habitats were characterized based on water temperature, turbidity, waterrncurrent, water pH, elevation, aquatic vegetation, habitat permanence, origin of thernhabitats (natural or human made), distance to the nearest house, presence of mats of algae,rnwater depth, intensity of shade, and substrate type. Logistic regression analysis detectedrnsix key environmental variables that were associated with the occurrence/abundance ofrnanopheline larvae: Water temperature, presence of mats of algae, water depth, and originrnof the habitats, turbidity and water current. Multiple step-up regression analysis furtherrndetected four best predictor variables associated with larval abundance of the malariarnvector species. Accordingly, relative abundance of An. gambiae s.l. larvae wasrnsignificantly and inversely associated with aquatic vegetation and water current whereasrnthat of An. pharoensis larvae were significantly and positively associated with waterrntemperature and the presence of algae in the water bodies. Dry season anopheline larvalrnhabitats that are created and maintained by perenial water bodies such as the EthiopianrnRift Valley lakes and rivers and their associated water development projects need to bernconsidered in vector control operation and further research.