Cinnamomi ramulus (called Guizhi in Chinese) is a traditional medicine used to treat gastrointestinal dysfunction, cancer, arthritis, osteoporosis, spleen deficiency, Alzheimer's disease and obesity. This review aimed to provide a systematic summary on the geographical distribution, botany, traditional application, phytochemistry, pharmacology, pharmacokinetics, toxicology and other aspects of Cinnamomi ramulus. So far, more than 121 chemical compounds have been isolated from Cinnamomi ramulus, including volatile oil, organic acids, triterpenoid saponins, coumarins, tannins, flavonoids and flavonoid glycosides, steroids and polysaccharides. This paper reviews the pharmacological effects of Cinnamomi ramulus on antibacterial, anti-inflammatory, antiviral, antitumour, antipyretic and analgesic, antidiabetic and antiplatelet aggregation effects. Furthermore, the present review also indicates that Cinnamomi ramulus has the potential to develop into drugs for treating various diseases with high efficacy and low toxicity. The convictive evidence from modern pharmacology research supports the traditional application of Cinnamomi ramulus. However, further studies on the structure-activity relationship of some of the isolated compounds may improve their biological potency. More toxicological studies will also contribute to the progress of clinical trial studies. © 2019 Royal Pharmaceutical Society.