The segmental distribution of visceral afferent neurons with axons in the cardiac nerve was studied in cats with the horseradish peroxidase (HRP) technique. After HRP was introduced into the left inferior cardiac nerve, labeled dorsal root ganglion cells were found in the ganglia from the C7 to T7 spinal levels, with a wide variation in distribution among the individual animals. An average of 93 cells was labeled per animal. The data indicate that the afferent nerve fibers in the inferior cardiac nerve project to a much wider range of segments of the spinal cord than previously believed.