Cerebral midline anomalies are defects of anatomical relationships between the two hemispheres. They include holoprosencephalies, septal and commissural agenesis. Agenesis of the olfactory tract (arhinencephalies) are often included in the spectrum of holoprosencephalies and the facial phenotype is thought to be affected and characteristic in the midline development abnormalities. This work concerns a review of the literature and personal experience in two units of Fetopathology in Paris. This study confirms the relationships between various cerebral malformations and their frequent association. However, arhinencephaly and moreover agenesis of corpus callosum should be considered as heterogeneous entities, often totally distinct and independent from the malformative process of the holoprosencephaly. In addition, if major facial anomalies such as cyclopia are almost pathognomonic for holoprosencephaly, minor malformations such as lateral facial clefts of cleft palates result from a great variety of malformative processes.