Calbindin (CB)-containing neurons in the cranial cervical, stellate, and celiac sympathetic ganglia of rats ( n = 60) aged 3-90 days were studied using an immunohistochemical method. The results obtained demonstrated that the stellate ganglion contained the greatest proportion of CB-immunopositive neurons. The proportions of CB-immunopositive neurons in the para- and prevertebral sympathetic ganglia decreased with age. The formation of the group of CB-immunopositive neurons in sympathetic ganglia was complete by the end of the first month of life.