In this study we assess the prey-mediated effects of Bacillus thuringiensis (Bt) Cry1Ab-expressed in maize on the performance and digestive physiology of the rove beetle Atheta coriaria (Coleoptera: Staphylinidae), using Tetranychus urticae (Acari: Tetranychidae) as prey in tritrophic bioassays. The toxin was detected in both T. urticae and A. coriaria adults and larvae, with concentrations of Cry1Ab decreasing through the trophic chain. In A. coriaria adults, the toxin decayed following an exponential curve, not being detectable in their bodies 24 h after the exposure to Bt-fed mites. When the performance of A. coriaria reared on (i) Bt maize infested with T. urticae, (ii) non-Bt maize infested with T. urticae, and (iii) rearing food were compared, no differences were found in any of the parameters analyzed (duration of immature stages, sex ratio, survivorship, fecundity and egg fertility). Proteolytic activities of A. coriaria adults fed with mites raised on Bt maize did not show differences with those reared on non-Bt fed-prey, indicating that the nutritional quality of the prey was not affected by exposure to the toxin. This work represents the first study dealing with prey-mediated effects of Bt maize on larvae and adults of a rove beetle. The use of this cosmopolitan rove beetle as an indicator species to assess potential effects of genetically modified crops on non-target arthropods is feasible.