Immunoreactivity for rat cerebellar calbindin, termed spot 35-calbindin, is transiently expressed largely in numerous small principal neurons of the superior cervical ganglion in pre-weanling rats and disappears by the fourth postnatal week. Preganglionic denervation results in a slower rate of disappearance of the immunoreactivity in ganglion neurons. This finding suggests that small principal neurons in the superior cervical ganglion may exert some yet to be determined Ca-mediated functions that are not shared with larger neurons at the pre-weanling stage. © 1991.