The vascularity of a peri-implant tissue is a very important parameter in the establishment and maintenance of healthy tissue after dental implant insertion. The purpose of this study was to compare the vascularity of the peri-implant mucosa between flap and flapless implant surgeries by using a canine mandible model. In six mongrel dogs, bilateral, edentulated, and flat alveolar ridges were created in the mandible. After 3 months of healing, 2 implants were placed in each side by either flap or flapless procedure. After another healing period of 3 months, biopsies were obtained, prepared for light microscopy, and exposed to morphometric measurements. The supracrestal connective tissue lateral to the implant was found to be more richly vascularized in the flapless group than in the flap group. These results suggest that the flapless procedure may increase the vascularity of the peri-implant mucosa.