The use of genetically modified organisms (GMO) in food is a highly public and controversial issue. We have used an enzyme-linked immunosorbent assay (ELISA) to detect the genetically modified protein 5-enol-pyruvylshikimate-3-phosphate (EPSP) synthase within soy-containing food products from the grocery store. We found that EPSP synthase is detectable in 3 out of 5 food products tested. Of specific interest, we found contamination levels of EPSP synthase (0.36%) in Heinz' Pablum Soya Cereal, which is currently deemed to be free of genetic modifications by the company as well as by Greenpeace Canada. These results demonstrate that genetically modified organisms are present in foods commonly available for human consumption and that the widespread use of this technology may make it difficult to ensure that any given product is free of all traces of genetically modified protein.