Background: Cinnamomum osmophloeum (Co), a member of the Lauraceae, is an indigenous medicinal crop in Taiwan, and it contains higher cinnamaldehyde in essential oil than do other Cinnamomum species. Among these species, Cinnamomum burmannii (Cb) is frequently adulterated as Co because of their similar morphological characteristics or features. Objective: The purpose of this study was to develop a DNA-based molecular method for rapid authentication of the indigenous Co and prevention of its adulteration. Materials and Methods: The internal transcribed spacer (ITS) regions of nuclear ribosomal DNA from various Cinnamomum species were amplified by polymerase chain reaction (PCR), and these obtained sequences were used for sequence analysis. Based on the sequence variants among various Cinnamomum species, restriction fragment length polymorphism (RFLP) was used to differentiate these Cinnamomum plants. Results: Two restriction endonucleases, MylI and EcoRV, were specifically used to digest the PCR-amplified ITS DNA from seven Cinnamomum species. The PCR-RFLP results demonstrated that the different restriction patterns that were produced by these two restriction enzymes clearly distinguished Co from Cb and five other Cinnamomum species simultaneously. Conclusion: The PCR-RFLP analysis developed in this study provides an alternative method for rapidly identifying Cinnamomum plants at the species level using DNA polymorphisms.