DNA barcoding is a taxonomic method that uses short DNA sequences from a particular region of the genome to provide a barcode for species identification. A desirable locus for DNA barcoding should be standardized, long enough to provide a large variation between species, and short enough to be easily sequenced with current technology. DNA barcodes in mitochondria (for animal), chloroplast and nuclear genomes (for plant) have been suggested. DNA barcoding using the cytochrome C oxidase I (COI) gene has been successfully used for species identification in the animal kingdom and has been adopted by the Consortium for the Barcoding of Life (CBOL) as the primary barcode sequence for animal. Internal transcribed spacer (ITS) of nuclear ribosomal DNA forms a universal DNA barcode marker for fungi. In plant kingdom, some useful markers to aid species identification are matK, rbcL, rpoC1, psbK-psbI, trnH-psbA, ITSAB. DNA barcoding plays an increasing role in taxonomy and the number of barcode in GenBank has grown exponentially in recent years. A library of DNA barcodes (The Barcode of Life Data System) was established to aid the acquisition, storage, analysis and publication of DNA barcode records. Studies using DNA barcoding are acting as a positive support to traditional morphology-based descriptive taxonomy. In Vietnam, substantial studies in the field of plant evolutionary biology based on analysis of DNA markers such as trnL, ITS and matK were carried out. These studies support and aid the growing demand for biodiversity conservation in Vietnam.