Arsenic poisoning has been discussed frequently in Norway during the past year on the background of a suspected crime case. There seem to be several uncertainties regarding this issue, also in the medical profession.We have searched the literature and made a review based upon the present knowledge about arsenic and arsenic poisoning.Arsenic can be found in numerous chemical compounds with different properties. Inorganic arsenic compounds, like arsenic trioxide, are reactive and can cause damage to the body. Organic arsenic compounds, which are found in high concentrations in fish and shellfish, are not considered toxic. Ingestion of inorganic arsenic affects cellular energy production; lethal poisonings can occur. Common clinical features after acute intoxication with arsenic are dysphagia, nausea, vomiting, abdominal pain, diarrhoea, intense thirst, and muscle cramps. Clinical features of chronic poisoning are hyperkeratosis in the palms and foot soles, pigmentation and conjunctivitis.Arsenic poisoning is a rare condition; its clinical features are uncharacteristic and the diagnosis must be confirmed by analysis of blood, urine and hair.