The seasonal abundance of the common larval andadult species: Culex pipiens, Cx. quinquefasciatus and Cx. sitiens wasexamined in four sea ports (Jeddah, Yanbu, Dubaand Haql) and two cities (Taif and Mecca) representingthe three regions of the western part of the Kingdom (Mecca, Al Madinah andTabouk) based on larval density (number per a survey unit, SU each of 10 dips)and adult density (number per a trap). Larvae were collected by dipping andadults by CDC, Black Hole and UV light traps biweekly from January 2013 toDecember 2014. The compiled density of the two years for each species in the differentlocalities and in all localities altogether was calculated. Cx .pipiens larvaebreed all year round with peaks of abundance were during autumn in Taif (78.02larva / SU), summer in Jeddah (38.59 larva / SU), spring in Tabouk (10.61 larva/ SU) and autumn for all areas altogether (21.63 larva / SU). Cx. quinquefasciatus larvae breed allyear round with peaks of abundance were during winter in Jeddah and Yanbu(128.92 and 36.04 larva / SU in the two localities, respectively) and for allareas altogether (34.54 larva / SU). Cx.sitiens larvae breed all year round in Jeddah, with peak of abundance wasin summer (77.67 larva / SU). Cx.pipiens adults were active all year round with peaks of abundance during autumn in Taif , Mecca and Yanbu (4.68, 4.97 and 3.96 adult / trap,respectively) and spring in Tabouk, and all areas together (9.50 and 5.36 adult/ trap, respectively). Cx. quinquefasciatus adults were active all yearround with peaks of abundance in spring in all localities either separately (Taif:11.07, Jeddah: 31.22, Yanbu: 1.93 and Tabouk: 7.78 adult / trap) except Meccawith peak during autumn (11.31 adult / trap) or in all areas altogether (11.06adult / trap). The obtained results are of importance in predicting the periodof maximum risk of bancroftian filariasis, Wuchereria bancrofti and WestNile Virus transmission and for carrying out an effective control program.