To evaluate, histometrically, the healing of gingival recession treated by coronally positioned flaps (CPF) with or without acellular dermal matrix (ADM) as a subepithelial graft. Gingival recessions were created on the upper cuspids of six dogs and were randomly assigned to: CPF+ADM (ADM group) or CPF alone (CPF group). After 4 months, the dogs were sacrificed, and the histometric measurements were performed. The epithelial length was 2.28 + 0.92 mm and 2.10 + 0.46 mm for the ADM and CPF groups, respectively (P=0.74). The connective tissue adaptation was 0.05 + 0.08 mm for the ADM group and 0.06 + 0.08 mm for the CPF group (P=0.36). The new cementum was 2.35 + 1.55 mm and 2.90 + 0.96 mm in the ADM and CPF groups, respectively (P=0.53). The new bone was 0.60 + 1.36 mm for the ADM group and 0.35 + 0.82 mm for the CPF group (P=0.53). The gingival recession was -0.88 + 1.33 mm in the ADM group and -0.21 + 0.22 mm in the CPF group (P=0.21). The gingival thickness was 1.63 + 0.28 mm in the ADM group and 1.16 + 0.20 mm in the CPF group (P=0.002).19128-32