In the current study, four entomopathogenic fungi(EPF) were isolated and identified as Aspergillus niger, Penicillium sp.s, Cunninghamella echinulate and Penicillium sp. for testing their virulence against Culex pipiens that represent a major vector for several pathogens. Based on the obtained data, these EPF exhibited a lethality effect against stages of C. pipiens after treating the newly 3^rd instar larvae. However, the effect was reflected in the hinder of pupation and adult emergence. The entomopathogenic fungus A. niger exhibited the lowest LC₅₀, 5.20E+13 (Spores/ml). EPF revealed a somewhat decrease in both % of pupation and adult emergence. Dramatically, EPF declined all metabolic substances; total carbohydrate, total lipid, and total protein in the treated insects. EPF in the current study proved its virulence against C. pipiens. However, it decreased the insect body metabolites.