This experiment was carried out at the Farm of Sakha Agricultural Research Station, Kafr El-Sheikh Governorate during the two successive seasons 2006 and 2007 to evaluate the role of insect predators of Aphis gossypii Glov. in cotton fields. The following predators were considerd during thecurrent resarch: Coccinella undecimpunctata (L.), Cydonia vicina isis, Cydonia vicina nilotica, Scymnus interruptus, Paederus alfierii, Chrysoperla carnea, Syrphus spp. and Orius spp. Results indicated that P. alfierii was recorded with the highest numbers followed by C. undecimpunctata., Syrphus spp., Sc. interruptus, Orius sp. and Ch. carnea (1452,1256, 1181, 1141, 1135, 1059 indiv/60 leaves). The associated predators were more in 2006 season than 2007 season. Population fluctuation of the cotton aphid, A. gossypii and the predator C. undecimpunctata were monitored on cotton plants during the two successive cotton seasons 2006 and 2007. The average number of the collected aphids in the second season were higher than those obtained during the first season; 29760 and 28755 indv./20 plants, respectively.               Some biological aspects of C. undecimpunctata were also studied as reared on A. gossypii. The larval stage of C. undecimpunctata was completed in four instars that collectively lasted 9.40 days. Adult female longevity averaged 59.00 days. However, the male longevity took a shorter period (49.60 days). One female deposited 441.59 eggs during the oviposition period with  a daily average of 11.56 egg/female. The preoviposition period took 8.8 days, oviposition 38.20 days, and the post oviposition 5.60 days