A3-year-old boy presented to the Hospital for Sick Children with systemic symptoms and oropharyngeal and peripheral extremity changes suggestive of Kawasaki disease. He was found to have severe hypertension. Investigation for a catecholamine-secreting tumor was negative. Toxins were considered when the patient's 20-month-old brother presented with similar symptoms, and the boys were subsequently diagnosed with elemental mercury poisoning. We review the literature on mercury intoxication and discuss the historical context, clinical syndrome (acrodynia), treatment, and radiologic findings of this unusual diagnosis.