A postmortem study of 64 vagus nerves from 32 children up to 1 year of age was done to determine the incidence of ectopic parathyroid tissue. The segments of nerve (average length, 2.6 cm), including the entire ganglion nodosum, were examined using a combination of step and serial sectioning. Discrete solitary collections of ectopic parathyroid chief cells were seen in 6% of vagus nerves and ranged in diameter from 162 to 360 micron. Confirmation of the nature of the cells was based on the presence of abundant glycogen and positive immunoreactivity for chromogranin and parathormone. The possible significance of intravagal parathyroid tissue is briefly discussed.