Botanical supplements for health enhancement are being increasingly used in the United States, but no safeguards are formally in place to ensure that they are not contaminated with non-efficacious or potentially harmful plant material. A molecular approach, which allows the authentication of botanical ingredients and detection of contaminating plant material by analyzing the ITS-1 region by PCR-RFLP and subsequent sequencing, is described. When using starting material from which DNA can be obtained, this method has the potential for identifying both primary and contaminating plant material in botanical dietary supplements.