We describe a modification of the DNA extraction method, in which cetyltrimethylammonium bromide (CTAB) is used to extract nucleic acids from plant tissues. In contrast to the original method, the modified CTAB procedure is faster, omits the selective precipitation and CsCl gradient steps, uses less expensive and toxic reagents, requires only inexpensive laboratory equipment and is more readily adapted to high-throughput DNA extraction. This protocol yields approximately 5-30 microg of total DNA from 200 mg of tissue fresh weight, depending on plant species and tissue source. It can be completed in as little as 5-6 h.