Cry9C protein in StarLink (SL) corn is an endotoxin produced from a gene derived from Bacillus thuringiensis (Bt). This method is a quantitative enzyme linked immunosorbent assay (ELISA) determination of Bt-modified corn in corn flour and meal. Proprietary antibodies, from Strategic Diagnostics Inc., specific for Cry9C protein are used. The method is calibrated to estimate the weight percent of modified corn in corn flour and corn meal.