The distribution of sural nerve afferent fibres within the spinal cord of normal adult rats and of adult rats treated at birth with capsaicin was examined using transganglionic transport of horseradish peroxidase (HRP). Labelled fibres were seen, in normal and in capsaicin-treated rats, in Laminae I-VI of the central third of the dorsal horn, extending rostrocaudally between the L3 and L5 segments. It is concluded that the changes in dorsal horn somatosensory systems induced by neonatal capsaicin are not due to anatomical redistribution of the areas of termination of peripheral nerves within the spinal cord.