Five cases are presented to document the use of an unusual barrier in the treatment of infrabony defects according to the principles of guided tissue regeneration. A rubber dam was positioned after flap elevation, defect debridement, and root planing to cover the defect and the surrounding bone. The dam was covered with the surgical flap and removed after 5 weeks. The 1-year clinical measurements and reentry procedure demonstrated the efficacay of the rubber dam as a barrier in guided tissue regeneration procedures.