Laboratory feeding experiments using transgenic Bacillus thuringiensis variety kurstaki (Berliner) corn plants were carried out to study the effects of B. thuringiensis-fed herbivorous prey on the predator Orius majusculus (Reuter). Host plants were a transgenic B. thuringiensis-expressing (Cry1Ab) corn hybrid and the corresponding untransformed isogenic B. thuringiensis-free corn hybrid. The herbivorous prey species used in the experiment was Anaphothrips obscurus (Müller), a thysanopteran pest of corn, not sensitive to Cry1Ab toxin. The objectives were to quantify the effects of B. thuringiensis-fed prey on the development and mortality of immature O. majusculus. There was no significant difference in total mean mortality from hatch to adult eclosion between O. majusculus nymphs reared on B. thuringiensis-fed or B. thuringiensis-free prey. Similarly, no significant differences in total developmental time of O. majusculus was detected when reared on the two different prey types. Overall mortality was low, confirming that the methodology used was appropriate. We propose this approach as an efficient standardized preregistrational testing for side effects of transgenic plants on small predators such as Orius spp.