The objective of this review is to systematically appraise the literature available to date on biological activities (in vitro and in vivo) of extracts and constituents from Cinnamomum. An extensive review of the literature available in various recognised databases including PubMed, Google Scholar and Scopus on the biological activities of various species of the Cinnamomum were undertaken. The literature provided information on biological activities of the species of the genus Cinnamomum. Crude extracts and constituents from about 30 species of Cinnamomum displayed significant antibacterial, antifungal, antiseptic, antiviral, anti-inflammatory, antipyretic, antioxidant, chemopreventive, cytotoxic, antidiabetic, hypolipidemic, antispasmodic, antiulcer, antiplatelet, anodyne, choleretic, immunostimulant, anaesthetic and sedative activities. Essential oil, aqueous/alcoholic extracts, cinnamaldehyde and proanthocyanidins were reported to be mainly responsible for biological activities displayed by most of the plants. Plants of Cinnamomum genus possess a wide spread of biological activities validating their use in traditional medicine. However, most of the available references lack information on active constituents, doses, duration of the treatment, storage conditions and positive controls for examining biological activities. The molecular mechanisms involved in eliciting biological activities were not comprehensively elucidated. Investigations to prove the safe use of these plants in traditional medicine are very limited. Thus, more studies on identification of bioactive constituents and their molecular mechanisms are needed. In addition, given that various species of Cinnamomum are being widely used in traditional medicine and culinary purposes, their main therapeutic aspects, toxicity, and adverse effects warrant further investigation in the future.