Multiplex PCR can simultaneously detect two or more products in a single reaction. There is an increasing demand for multiplex PCR techniques in assays conducted in research laboratories and forensic/diagnostic genotyping assays (1,2). Multiplex PCR can also be used for semi-quantitative gene expression analysis using cDNA templates. The NEB Multiplex PCR 5X Master Mix is an easy-to-use solution featuring high quality recombinant Taq DNA Polymerase. The mix is optimized for high yield and robust performance. Its performance is illustrated in a 15-plex PCR using human genomic DNA (Figure 1) and an 8-plex PCR using cDNA products as templates (Figure 2). The 5X formulation allows the user maximal input of primers, template DNAs and additional components.