Thallium intoxication in a 28-year-old woman was characterized by neurological and gastrointestinal symptoms and alopecia. Treatment was started 4 days after poisoning and consisted of forced diuresis and administration of Prussian Blue at four daily doses of 5 g by duodenal tube for 20 days. Thallium was measured by atomic absorption spectrophotometry in urine, faeces and saliva. Considerable amounts of thallium were detected in saliva, salivary concentrations being up to 15 times higher than urinary ones. Evidence was also obtained that only a little fraction of the ingested dose was excreted by the intestine during the hospital course in spite of Prussian Blue administration.