A circular calvariectomy procedure was performed on 24 New Zealand white rabbits at 6 weeks of age. In 12 animals, the continuity of the dura mater was interrupted. The remaining animals served as controls. The animals were sacrificed at intervals to document the regenerative potential of the altered dural tissues. The results of this experiment show that bone deposition leading to calvarial redevelopment is directly dependent upon the presence of the dura mater. In addition, the rate of deposition is apparently affected by dural continuity, animal age, and localized differences in the thickness of the dural layers. The redevelopment and patency of the cranial sutures are strongly influenced by alterations in the continuity of the dura mater.