Noni (Morinda citrifolia L., Rubiaceae) is a tropical and subtropical plant grown in the Paciﬁc islands and has been used traditionally as a folk medicine to treat a broad range of diseases for over 2000 years. Commercial noni juice and encapsulated noni powder have become popular in Asia, North America, and Europe. Various unsubstantiated claims are currently made for noni products, such as func-tions as an immune system stimulant, anticancer agent, menstrual cycle regulator, or blood cleanser. Biological compounds such as glycosides, polysaccharides, iridoids, alkaloids, lignans, trisaccharide fatty acid esters, anthraquinones, scopoletin, morindin, vitamins, and minerals have been isolated from noni fruits, roots, and leaves. In vitro and in vivo laboratory experiments on functions of noni juice, extracts, or isolated biological compounds demonstrate that noni can confer health beneﬁts in the form of scavenging of free radicals, antimutagenicity, anticarcinoma activity, anticlastogenic activity, inhibition of lowdensity-lipoprotein oxidation, anti-inﬂammatory activity, blood puriﬁcation, stimulation of the immune system, regulation of cell function, and regulation of cholesterols.