Thallium is a toxic and rare heavy metal. There are several common pathways for acute intoxication of thallium to human being, such as respiratory, digestive or dermal route, especially the oral way. It is known that the inhibition of potassium in Na+-K+-ATPase, the alteration of membrane physical properties, the binding with thiol enzyme, the impaired mitochondrial function and interaction with riboflavin to disrupt electron transfer may play a role in thallium toxicity. The exact mechanisms still remain poorly understood. Neurotoxicity is the most prominent clinical symptom for thallium toxicity. When a person showed symptoms of alopecia, peripheral neuropathy together with gastrointestinal disorders, it is reasonable to consider the possibility of thallium toxicity. When the value of thallium level in blood or urinary is more than 100 μg/L or 200 μg/L, it can be used for diagnosis of thallium toxicity. Oral consumption of Prussian and blood purification are main strategies for thallium detoxification.