Seckel's syndrome is a rare form of primordial dwarfism, characterized by peculiar facial appearance. In the past, this condition was overdiagnosed, and most attention was given to the facial and skeletal features to define more precise diagnostic criteria. The presence of mental retardation and neurologic signs is one of the peculiar features of this syndrome, but only recently were rare cases of malformation of cortical development described, as documented by magnetic resonance imaging (MRI). Here, we present three new cases of Seckel's syndrome showing different malformations of cortical development (one gyral hypoplasia, one macrogyria and partial corpus callosum agenesis, and one bilateral opercular macrogyria). We hypothesize that the different types of clinical expression of our patients could be explained by different malformation of cortical development types. We think that MRI studies could be performed in malformative syndromes because of the possible correlations between type and extent of the lesion and the clinical picture of any individual case.