A new polymerase chain reaction (PCR)-based method was developed to detect cows' milk in goat cheese. This method is based on mitochondrial DNA (mtDNA) control region sequence variations. DNA extractions from 150 mg of cheese were carried out using a spin column-based method. Subsequent PCR amplifications of DNA were performed with cow specific primers, demonstrating the ability to detect cows' milk in a variety of cheeses. This simple approach provides high quality DNA, and is shown to be very sensitive, with a detection limit of less than 0·1% of cows' milk. Analysis of an agarose gel digital image allows a rough estimation of the percentage of cows' milk used in adulteration.