The ecotoxicological effects of transgenic maize-expressed vaccine protein, Escherichia coliheat-labile enterotoxin subunit B (LTB), on two soil invertebrates were studied under laboratory settings. After being reared for 28 days on LTB-maize-treated soils, no apparent mortality of the springtail, Folsomia candida, or the earthworm, Eisenia fetida, was observed at levels well above conservatively projected estimated environmental concentrations. Therefore, it is concluded that there would be no acutely toxic effect of LTB to these species. As for the subacute effect, no significant differences of F. candida mean reproduction and E. fetida mean growth were observed between LTB-maize-treated samples and non-GM-maize-treated controls. In addition, no LTB was detected in the E. fetida whole-body extraction assay, which indicates there was no tendency for bioaccumulation. On the basis of these observations, it is predicted that any adverse effects of LTB-maize on F. candida and E. fetidawould be minimal, if any.