The Australian cotton industry relies heavily on transgenic cotton expressing Bt (Bacillus thuringiensis) toxins for the effective control of the major pest Helicoverpa. The use of Bt crops has dramatically reduced chemical pesticide usage, meaning there is now a greater emphasis on integrated pest management strategies such as biological pest control using natural enemy insects. This study divulged the possible effects of the Bt toxins, specifically Cry2Ab, on natural predators and parasitoids. Two non-target beneficial insects were studied, one hemipteran predator, Nabis kinbergii, and one dipteran parasitoid, Carcelia illota. It was shown that the development time to adulthood, and the adult length and weight of N. kinbergii feeding on resistant H. armigera larvae fed Cry2Ab toxin were not affected. This suggests that N. kinbergii are able to effectively predate Helicoverpa in Bt fields. Adult length and weight of C. illota was shown to be unaffected by feeding on resistant larvae fed Cry2Ab toxin. However, there was some effect from the Cry2Ab toxin and/or the resistant genotype on the juvenile development of C. illota. This needs further investigation to determine the physiological significance, but to the best of my knowledge this effect does not transfer into adult flies, meaning C. illota are still able to effectively parasitise Helicoverpa thereby minimising the population in Bt cotton crops.