Anopheles populations were monitored for one year in 2 neighboring villages in Faiyum Governorate, Egypt, to study factors causing differences in malaria prevalence. Both villages contained the following species: Anopheles pharoensis, An. sergentii, An. multicolor and An. tenebrosus. Abundant larval breeding sites in Abheet, the village with the higher malaria rate, accounted for the higher adult densities observed from human and animal biting collections and from indoor resting collections. Anopheles pharoensis and An. sergentii were the dominant species in Abheet with seasonal biting activity extending from May to December, reaching a peak in November. In El Zawya, the village with the lower malaria rate, An. pharoensis dominated, reaching seasonal peaks in June and August. Inside houses, An. sergentii was common from May to January in Abheet, but rare in El Zawya. Anopheles pharoensis and An. sergentii were both incriminated as malaria vectors based upon their seasonal abundance and the finding of sporozoite positive specimens during the peak malaria season.