Xanthones (9H xanthen-9-one) are an important class of heterocyclic compounds containing oxygen and moiety of gamma-pirone, dense with a two-benzene ring structured, distributed widely in nature. Naturally occurring xanthones are found in micro-organisms and higher plants as secondary metabolites in fungi and lichens. Compounds of the family Calophyllaceae, Guttiferae and Gentianaceae are the most common natural source of xanthones. The structure of xanthones nucleus, coupled with its biogenetic source, imposes that the carbons are numbered according to the biosynthetic pact. The characteristics oxygenation pattern of xanthones earlier is mixed shikimate-acetate biogenesis. The major class of xanthones includes simple oxygenated, non-oxygenated, xanthonolignoids, bisxanthones, prenylated and related xanthones, as well as miscellaneous xanthones. Their great pharmacological importance and interesting scaffolds were highly encouraged by scientists to investigate either the synthesis design or natural products for cancer treatment. Because currently used antitumor drugs possess high toxicity and low selectivity, efficacious treatment may be compromised. This review is limited to the antitumor activity of xanthones and the chemistry of xanthone core, which may help provide fundamental knowledge to the medicinal chemist for new and advanced research in drug development.