Three additional children under 12 years of age with functionally active pheochromocytomas are presented. These three children are of further interest becaues of the familial nature of the pheochromocytomas. Two of the cases are the first to be reported in sisters less than 10 years of age. These two sisters demonstrate that children may have multiple pheochromocytomas, located both within the abdomen and in the chest. The older of the two sisters had an intrathoracic pheochromocytoma as well as pheochromocytomas of both adrenal glands. The younger sister had a pheochromocytoma of the right adrenal gland and another in the region of the aortic bifurcation. Of striking interest was the finding of bilateral pheochromocytomas in the mother of the two girls. This is the first report in which a mother and her children had functionally active pheochromocytomas. The literature is reviewed and the characteristics of these tumors as well as the laboratory diagnosis are discussed.