Investigating prenatal neural development provide depth knowledge of brain ontogeny. DTI-derived radial diffusivity (RD) imaging has advantage to provide information of microstructural tissue organization information without damaging the tissues. In this study, we investigate the changes of the radial diffusivity (RD) values during fetal development in non-human primate. The RD image contrast was enough to clearly depict the emergence of each brain regions as well as major white matter bundles during prenatal period. In addition, its whole brain intensity distribution histogram provided the information of critical period for the growth of myelination.