Dioxin may refer to: * 1,2-Dioxin or 1,4-Dioxin, two unsaturated heterocyclic 6-membered rings where two carbon atoms have been replaced by oxygen atoms, giving the molecular formula C4H4O2 * Dibenzo-1,4-dioxin, the parent compound also known as dibenzodioxin or dibenzo-p-dioxin (molecular formula C12H8O2), in which two benzene rings are connected through two oxygen atoms * Dioxins and dioxin-like compounds, a diverse range of chemical compounds which are known to exhibit "dioxin-like" toxicity * 2,3,7,8-Tetrachlorodibenzodioxin (TCDD), the prototypical example of the above class, often referred to simply as "dioxin"