Dioxins and dioxin-like substances are highly toxic and extremely dangerous chemical compounds. Dioxins are formed during the thermal process associated with the use of chlorine. 2,3,7,8-tetrachlorodibenzo-1,4-dioxin is the most toxic, the most typical and well-studied agent. The most characteristic and constant indicators of intoxication with dioxin-containing substances are altered body weight, chloracne, hepatic damage, thyroid involution, structural changes in the adrenal cortex, spleen, genitals, immunodeficiency. There is evidence for a role of these agents in the development of infertility and neonatal pathology.