The determination of genomic DNA sequence flanking a known region is often problematic. Existing technologies depend on multiple, efficient enzyme-catalysed preparative processing steps and/or rely on relatively inefficient one-sided' PCR mechanisms. I demonstrate the application of a simple two-sided' PCR-based approach, lariat-dependent nested PCR for rapid amplification of genomic DNA ends (LaNe RAGE), applied to the mouse GAPDH and PGK1 gene flanking sequences. This demonstration offers great promise in applications such as genome walking, transposon mutagenesis mapping and DNA fingerprinting