Cotton bollworm, Helicoverpa armigera, is the main insect pest of cotton plant in Turkey and most part of the world. The aims of this study was to determine susceptibility levels of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) strains collected from cotton fields in Adana and Mardin provinces to registered seven insecticides in Turkey. Third instar larvae of H. armigera were used to determine the LD50 values by using topical application method with active substances of commonly used insecticides for controlling H. armigera in cotton fields. The active substances were azinphos-methyl, bifenthrin, beta-cyfluthrin, esfenvalerate, indoxacarb, lambda-cyhalothrin and methomyl. Insects were treated on the region of the body between the head and the abdomen, thorax, with 1 mu l aliquots of insecticides in acetone for all treatments and acetone alone for control. Results showed that Adana and Mardin strains had high resistance ratios to pyrethroid insecticides such as beta-cyfluthrin, bifenthrin and esfenvalerate, whereas they did not have significant resistance for indoxacarb and methomyl. These results can be used in the resistance management programs for the control of H. armigera in the region.