The injection of endothelin-1 (ET-1) (2 pmol) into the dorsolateral periaqueductal gray area (PAG) of mice produces antinociceptive effect as underscored by increases in the latency time for the reaction to a hot plate. Pretreatment of the PAG area with bosentan (10 nmol) (a mixed ET(A)/ET(B) receptor antagonist), FR 139317 (5 nmol) (ET[A] receptor selective antagonist) or BQ-788 (5 nmol) (ET[B] receptor selective antagonist) greatly reduced the antinociceptive effect induced by ET-1. Therefore, ET-1 induces antinociceptive effects via both ET(A)/ET(B) receptors. In addition, since ET-antagonists lowered per se the control reaction time of the mice when administered alone to the PAG area, we would suggest that endogenous ET-1 acting within the PAG area contributes to the suppression of pain.