A case of accidental Thallium intoxication showing, as the only sign, alopecia of the scalp with depigmentation of the hair, is described. A 21 year old woman developed acute loss of hair after ingestion of contaminate tomatoes. No further signs of intoxication were evident. The diagnosis has been made by evidencing Thallium in the urine (colorimetric method) and in the hair (atomic absorption spectrophotometry). Moreover, the clinical and histopathological findings of Thallium alopecia are described.