Objective: to study reelin expression in the neocortex of fetuses and newborns with internal hydrocephalus (HC) and to reveal its features in relation to the etiology of HC. Material and methods. The brains of fetuses and newborn at 22—40 weeks’ gestation with internal HC associated with Sylvian aqueduct malformation (n=9), post-inflammatory (n=4) and post-hemorrhagic (n=5) HC were examined. In a comparison group, the fragments of brain tissue with a slit-like lumen of the lateral ventricles were no more than 0.5 cm (n=20). A standard immunohistochemical method was used to reveal reelin expression in the neocortex of the anterior third of the precentral gyrus. Results. HC associated with Sylvian aqueduct malformation is characterized by a negative reelin immunoexpression. In postinflammatory HC, the expression of reelin decreases significantly (p=0.025) with respect to the conditional norm and, in posthemorrhagic HC it is comparable with that in the comparison group. Conclusion. The features of reelin expression in the brain of fetuses and newborns at 22—40 weeks’ gestation with internal HC should be considered as morphological differential and diagnostic criteria for the disease in relation to its etiology.