Abstract: Genetically modified crops are widely grown in the world today. Labeling is required when genetically modified organisms (GMOs) are placed on the market. There is a need to establish a specific method for the detection of genetically modified foods. MON863 transgenic maize containing a Cry3Bb1 sequence that produces insecticidal protein cry3Bb1 is a major GMO crop. In this paper, we report studies that designed specific PCR primers and TaqMan probes based upon the 5′-transgene integration sequence, and developed qualitative and quantitative PCR conditions using these primers and probes. We determined the 5′-transgene integration sequence using a ligation-mediated polymerase chain reaction (LM PCR) method. In qualitative PCR studies, the limit of detection (LOD) was 0.5% for MON863 in 100ng genomic DNA. In the quantitative PCR assays, the limit of detection (LOD) and limit of quantitation (LOQ) are 10 and 100 haploid copies, respectively. Maize samples with different contents of genetically modified component were tested using the established TaqMan real-time PCR system. [Copyright &y& Elsevier]