Aphids are very serious pest in greenhouses and field in many countries. The toxicity of two insecticides with different mode of action and three petroleum ether plant extracts were tested against two aphid species; Brevicoryne brassicae L, and Aphis craccivora koch in the laboratory using leaf-dip bioassay. The toxicity index showed that the carbamate insecticide, primicarb has the highest aphicidal activity. Based on the LC50 values, primicarb was the most toxic compound with LC50S of 0.12 and 0.26 mg/L against B. brassicae and A. craccivora, respectively. Imidacloprid was the least toxic compound against B. brassicae with LC50 of 2.14 mg/L. Against A. craccivora, henbane extract was the least toxic compound (LC50=19.7 mg/L.). The results indicated that field efficiency of primicarb and imidacloprid were compatible with the laboratory results. However, plant extracts showed opposite results under field conditions.