There are numerous and evidential findings that TCDD (2, 3, 7, 8-tetrachlorodibenzo-Pdioxin, or dioxin) is a potential carcinogen and general toxin in rodents. flowever, human risk assessment for dioxin exposure has been a topic of debate, owing in part to the large animal interspecies differences in its toxicity. We review dioxin-related reports indicating its toxicity, toxic effects in animal, and human epidemiologic findings. The intent of this paper does not provide a causal inference about chronic human diseases related to dioxin exposure. This summary would give a valuable clue for a researcher to conduct or design a further dioxin-related study.