InterL The rates of infestation of Canola plants with aphids and their associated parasitoids were studied, in the Research Stations, at Zarzoura and El-Nubariya (El-Beheira Governorate) and Sakha fields (Kafr El-Sheikh Governorate) through December 2004 till April 2005. Also, the rates of aphid parasitism, emergence of parasitoids and their sex ratio were determined. Results showed that the cruciferous aphid Brevicoryne brassicae (Linnaeus) was recorded from the three districts. Aphid populations increased during the periods of development and flowering of Canola plants and reached the highest levels in Nubariya than in Zarzoura and Sakha fields. The rate of parasitism was highest during March reaching 78.00, 90.00 and 58.00% in Zarzoura, El-Nubariya and Sakha fields, respectively. A positive correlation was observed between the rate of aphids' parasitism and the emergence rate of parasitoids. The sex ratios of the emerged parasitoids recorded were 1: 1.1 or 1.2 (Males: Females). The identified parasitoid species were Diaretiella rapae (McIntosh) and Ephedrus sp. (Hymenoptera: Aphidiidae). D. rapae was the most common parasitoid emerging from the collected samples at the three localities. Ephedrus sp. did not emerge from aphid samples at Sakha fields but it occurred by late March and early April in Canola fields at Nubariya and in mid February at Zarzoura. The hyperparasitoid species, Alloxysta sp. (Hymenoptera: Cynipoidea: Charipidae: Alloxystinae) occurred associated with the primary parasitoids at Zarzoura fields only in April. AI: Y BT: Nutrition-; Diet-; Life-cycle-and-development; Development-; Metamorphosis-; Parasites-diseases-and-disorders; Parasites-; Insect-parasites; Hosts-; Insect-hosts; Ecology-; Population-dynamics; Population-structure; Land-zones; Palaearctic-region; Africa- Alloxysta-, Diaretiella-rapae, Ephedrus-: Emergence-, Emergence-rate, Hemipteran-hosts, Brevicoryne-brassicae, Prevalence-and-emergence-rate, host-food-plant-crop-regional-comparisons, Population-sex-ratio, Egypt-, Nubariya-, Sakha-and-Zarzoura; Brevicoryne-brassicae: Food-plants, Brassica-napus-and-Brassica-rapa, Hymenopteran-parasites, Diaretiella-rapae, Ephedrus-and-Alloxysta, Prevalence-and-emergence, food-plant-crop-regional-comparisons, Egypt-, Nubariya-, Sakha-and-Zarzoura S1: Ephedrus- (Aphidiidae-): Parasite-; Diaretiella-rapae (Braconidae-): Parasite-; Alloxysta- (Cynipidae-): Parasite-; Brevicoryne-brassicae (Aphidoidea-): Host- ST: Insecta- , Hymenoptera- , Apocrita- , Terebrantia- , Ichneumonoidea- , Aphidiidae-; Insecta- , Hymenoptera- , Apocrita- , Terebrantia- , Ichneumonoidea- , Braconidae-; Insecta- , Hymenoptera- , Apocrita- , Terebrantia- , Cynipoidea- , Cynipidae-; Insecta- , Hemiptera- , Homoptera- , Sternorrhyncha- , Aphidoidea- none2006