 Focal cortical dysplasias (FCDs) are malformations of cortical development that present cortical dyslamination and abnormal cell morphology and are frequently associated with refractory epilepsy. FCD type IIb presents dysmorphic neurons (DNs) and balloon cells (BCs), which are the hallmarks of this dysplasia. Moreover, hypertrophic neurons (HyNs) may be present in FCD types I, II and III. The objective of this study was to perform a detailed morphology and immunophenotype study of BCs, DNs, and HyNs in a cohort of FCD IIb patients.