We report the case of a family in which the mother died of hypertensive encephalopathy following the relapse of a phaeochromocytoma. Two of her children are still alive. Both children had malignant phaeochromocytomas that have been treated by surgery and 131I-MIBG. The first child presented with phaeochromocytoma of the right suprarenal gland at the age of 7 years. Surgery was performed. At the age of 14 years, he developed a tumour of the left suprarenal gland and two pulmonary metastases demonstrated by 131I-MIBG. The three tumours were removed, but new lesions occurred. The boy then was treated with 200 mCi (7,400 MBq) of 131I-MIBG given twice, and is now free of disease more than 2 years after treatment. His sister presented at the age of 12 years with phaeochromocytoma of the left suprarenal gland, the only lesion recognized by 131I-MIBG. The tumour was removed, but 5 months later, she developed phaeochromocytoma in the right suprarenal gland. She was treated with 200 mCi (7,400 MBq) of 131I-MIBG and surgery was performed 6 months later. Histology of the suprarenal gland could not demonstrate the persistence of phaeochromocytoma cells. The child is now free of disease more than 2 years after treatment.