Extracellular recordings were made in the thalamic posterior nuclear group of anesthetized rats to study the effects of SR48968, a non-peptide NK2 receptor antagonist, on the responses evoked by thermal or mechanical nociceptive cutaneous stimulation. SR48968 (0.125-0.5 mg/kg, i.v. route) inhibited the responses to thermal stimulation while being ineffective on mechanically evoked responses in doses up to 2 mg/kg i.v. This effect was stereoselective since SR48965, the (R) enantiomer of SR48968 with a 2000-fold lower affinity for NK2 receptors, did not modify thermally evoked responses at a dose of 1 mg/kg i.v. These results support the notion that NK2 receptors are involved in thermal nociception.