DIAGNOSIS of tumors of neural crest origin—neuroblastoma, ganglioneuroma, ganglioneuroblastoma, and pheochromocytoma— has been aided by biochemical tests which measure increased urinary excretion of certain metabolites of the naturally occurring catecholamines: norepinephrine (NE), epinephrine (E), dopamine (DM) and dopa (DA).1-13This provides rapid identification of the general tumor type preoperatively and offers a laboratory guide for evaluating the efficacy of treatment. Chemical analyses of tumor tissue2,5,14-19as well as electron microscopy19,20have provided additional information concerning the secretory nature of these tumors. These studies evolved from a recognition of the embryological relationship between these tumors and other known catechol-producing tissues: the adrenal medulla, sympathetic nerves, and ganglia. The adrenergic mediator, 1-norepinephrine, is produced in sympathetic nervous tissue following a well-defined chemical sequence starting with tyrosine (Fig 1). In the adrenal medulla, the identical chemical transformation takes place, following which NE may be methylated to 1-epinephrine. These two