The relative roles of receptors for AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid) in spinal nociceptive and non-nociceptive transmission were studied on dorsal horn wide dynamic range neurones in alpha-chloralose-anaesthetized spinalized rats. The effects of systemically administered competitive and non-competitive AMPA antagonists (the quinoxalinedione NBQX and the 2,3-benzodiazepine GYKI 53655) were examined on responses to peripheral noxious heat and non-noxious tap stimuli as well as to iontophoretic AMPA and N-methyl-D-aspartate (NMDA). Both NBQX and GYKI 53655 dose-dependently reduced responses to peripheral stimuli and to AMPA. GYKI 53655, the more selective antagonist of AMPA vs NMDA, decreased heat and tap responses to the same extent. The results indicate that AMPA receptors play a significant and equal, but not exclusive, role in mediating nociceptive and non-nociceptive spinal transmission.