The rodent population and their ectoparasites especially fleas, in various Egyptian eco-geographical areas were studied It was noticed that flea infestation varied according to rodent species and to the bioclimatic conditions. High flea indices were recorded in certain seasons of the year. The flea index was above one during spring in the southern of Nile Delta and semi-arid coastal areas, in summer in northern coastal areas and in autumn in southern of Nile Delta. Susceptibility tests were conducted using the WHO diagnostic dose of malathion (5%) on three populations of fleas collected from Qualyobia, Suez and Beni-Suef Governorates. The results indicated that malathion (5%) was very effective on fleas collected from Beni-Suef and Suez, but there was an evidence of increased tolerance among flea population collected from Qualyobia Governorate.