A practical class experiment based on the extraction/purification of DNA from soybeans and the identification of exogenous DNA sequences amplified by PCR is described. This is used in a biochemistry and molecular biology course for advanced science undergraduate students. Students are given small amounts of soybean powder, and they practice a DNA extraction, purification, and a PCR with a set of different specific primers followed by an electrophoresis to determine whether the sample is transgenic. A major aim is to provide experience in the use of common techniques such as DNA extraction/purification and PCR and their interpretation.