During spinal cord (SC) regeneration in the tail of Rana dalmatina tadpoles few neurons are regenerated from the ependymal epithelium. Using microscopic methods, immunofluorescence, tract tracing and electron microscopy, the present study has analyzed the cells generated in the caudal SC during the first 20 days of regeneration under normal and stress conditions. Since early larval stages, the regenerating SC contains few nerve cells (2-3%) and more numerous immune cells (5-7%), namely heterophil granulocytes, macrophages and lymphocytes. Few regenerated nerve cells are connected to the normal SC by axons detected after application of the retrograde fluorescent tracer Dil. Cell degeneration in the regenerating SC is commonly observed, including also loss of nerve cells, a process that occurs well in advance from metamorphosis. Furthermore, under lightly stress conditions, when tadpoles are kept in agitated water during tail regeneration, nerve degeneration and the number of immune cells significantly increases in the regenerating SC, a mean of 13.5% versus 5.6% in normal conditions. The study shows that normal and regenerating SC are under immune surveillance since early tadpole stages, well in advance of metamorphosis when immune cells determine the degeneration of the SC and the complete reabsorption of the tail.