The aim of this study was to histologically evaluate the viability of mechanically expanded subepithelial connective tissue grafts. Sixteen samples of palatal connective tissue were collected from eight beagle dogs. Half of the samples were subjected to the expansion procedure and used as subepithelial grafts in the canine region, and the samples not subjected to expansion were grafted at the contralateral side. After 60 days, biopsies were collected and examined histologically by light and confocal laser microscopy and immunohistochemically with anti-CD31 antibody for endothelial cells. There were no significant differences between the control and test groups. It was concluded that this new method to expand the area of connective tissue grafts was not only viable biologically, but also decreased surgical risks without increasing processing time.