A 12-month-old girl is described with subacute onset of behavioral regression, arterial hypertension and itching erythema of the hands and feet with pink palms and soles. She was irritable and depressed, she had general weakness and refused to walk and eat. Mercury poisoning was suspected only after two months of extensive investigations to exclude infectious, autoimmune, neoplastic pathologies. The parents confirmed that a sphygmomanometer was broken in the girl's room two months before the onset of symptoms. The removal of the child from the source of the exposure was sufficient for the complete resolution of the pathology.