Among the factors affecting the efficiency of soft oral tissue healing is endothelin-1 (ET-1), a potent vasoactive peptide produced hom a biologically inactive big ET-1 by the action of endothelin-converting enzyme-1 (ECE-1). We investigated the expression of ECE-1 during buccal mucosal ulcer healing in rats maintained for 5 weeks on alcohol containing or control diet. The mucosal activity of ECE-1, characterized by sensitivity to phosphoramidon, was associated with microsomal fraction and showed an elevated (3.1-fold) level in the alcohol diet group. Moreover, the ulcer onset in the alcohol group was reflected in a 39% greater expression of ECE-1 activity, and was accompanied by a 1.4-fold greater increase in TNF-alpha and a 2.5-fold greater enhancement in epithelial cell apoptosis. While in both groups the ulcer healing was associated with a decrease in buccal mucosal expression of ECE-1, as well as a decline in TNF-alpha and apoptosis, the changes were significantly slower in the alcohol diet group and manifested by a 40% delay In healing. Thus, chronic alcohol ingestion leads to up-regulation of ECE-1 expression, induction of TNF-alpha, and triggering apoptotic events that delay the mucosal repair.