Water collections which may provide breeding habitats for mosquitoes in Qalyubiya Governorate were surveyed throughout the period from April 2009 to March 2011. Mosquito larvae were collected on monthly basis from 14 different breeding places in eight villages. A total of 1800 from 2821 sites (63.8%) were found positive for mosquitoes, including 312 canals, 271 pools, 191 unused wells, 166 rice fields, 142 irrigation channels, 130 ponds, 128 drainages, 115 catch basins, 85 irrigation basins, 82 ditches, 70 swamps, 66 temporary pools, 22 unused tires and 20 irrigation drainage tubes. Mosquito larvae were found in a variety of water collections including temporary, permanent, natural or man-made habitats. Permanent and semipermanent water collections were the main sites for mosquito breeding. Nine mosquito species were identified in the study area namely, Culex pipiens 64.7%, Culiseta longiareolata 13.5%, Cx. antennatus 8.8%, Aedes caspius 6.3%, Cx. vagans 2.5%, Cx. decens 1.9%, Cx. perexiguus 0.9%, Cx. univittatus 0.8% and Anopheles multicolor 0.6%. Simple and Multiple regression models showed that temperature, Ammonia and Nitrate were the best predictors for mosquito larval density (P = 0.0397), (P = 0.0241) and (P = 0.0040), respectively. The year-round presence of immature mosquitoes indicates that climatic conditions of the area are not limiting to the development of most prevailing mosquito species. Catch basins, unused wells and drainages are playing the major role in mosquito problem in Qalyubiya Governorate.