In recent years, cranial distraction osteogenesis (DOG) for craniosynostosis has often been performed in Japan. Since 1998, DOG has been conducted in more than 80 patients with craniosynostosis in our institution. It is now important to define the appropriate indications for the application of DOG for craniosynostosis. From the point of view of our more than 10 years of experience with the application of cranial DOG, posterior enlargement is one of the most appropriate applications. Bilateral posterior expansion is conducted for hypertension because of bilateral lambdoidal synostosis, whereas unilateral posterior expansion is conducted for asymmetry because of unilateral posterior plagiocephaly. Posterior expansion by gradual distraction was conducted for 12 cases. Eight cases of syndromic craniosynostosis and 4 of simple unilateral lambdoid synostosis were included. Clinical and radiological improvement was observed in all cases. Postdistraction computed tomography demonstrated a decrease in digital printing within a few months in all cases. Distraction osteogenesis is a useful procedure for posterior enlargement by gradual expansion and guarantees postdistraction rigidity without collapse in a supine position in bilateral and unilateral lambdoid synostosis.