OBJECTIVE: In this article, we review the normal anatomy and development of the posterior skull base and describe distinguishing imaging features of the two most common causes of posterior plagiocephaly: posterior deformational plagiocephaly and unilateral lambdoid synostosis. We also describe three unusual cases of posterior plagiocephaly, including asymmetric premature fusion of the anterior and posterior intraoccipital synchondroses, with diagnoses enabled by volume-reformatted MDCT. CONCLUSION: Three-dimensional reformatted MDCT enables accurate diagnosis of common and rare causes of posterior plagiocephaly in children.