Homozygous mutations in the cyclin-dependent kinase-5 regulatory subunit-associated protein 2 gene CDK5RAP2 cause primary autosomal recessive microcephaly (MCPH). MCPH is characterized by a pronounced reduction of brain volume, particularly of the cerebral cortex, and mental retardation. Though it is a rare developmental disorder, MCPH has moved into the spotlight of neuroscience because of its proposed central role in stem-cell biology and brain development. Investigation of the neural basis of genetically defined MCPH has been limited to animal studies and neuroimaging of affected patients as no neuropathological studies have been published. In the present study, we depict the spatiotemporal expression of CDK5RAP2 in the developing brain of mouse and human. We found intriguing concordance between regions of high CDK5RAP2 expression in the mouse and sites of pathology suggested by neuroimaging studies in humans and mouse. Our findings in human tissue confirm those in mouse tissues, underlining the function of CDK5RAP2 in cell proliferation and arguing for a conserved role of this protein in the development of the mammalian cerebral cortex.