This paper presents a real-time PCR method allowing the detection of traces of white mustard ( Sinapis alba ) in complex food matrices. The primers and the probe are targeted at the gene coding for S. alba MADS D. The real-time PCR method was found to be specific for white mustard and did not show any cross-reactivity with 67 biological species, including 12 members of the Brassicaceae family. The limit of detection, determined by analyzing serially diluted white mustard DNA extracts, was 1 pg of white mustard DNA/μL, corresponding to 5 pg of white mustard DNA. In model sausages, the limit of detection was found to be 0.001% white mustard (corresponding to 10 ppm or 10 mg/kg). The real-time PCR method was applied to verify the correct declaration of 20 foodstuffs purchased from Austrian supermarkets. White mustard DNA was detected in one of three samples labeled with "may contain traces of mustard" and in one of seven samples without any information on the presence of mustard.