Polymicrogyria is a brain malformation due to abnormal cortical organization. Two histological types, unlayered or four-layered can be distinguished. Polymicrogyria is a rare manifestation of chromosome 22q11 deletion syndrome. We report two boys with chromosome 22q11 deletion syndrome and polymicrogyria, and describe the neuropathological features of the malformation in one of them. Clinical examinations, EEG, brain MRI, chromosomal analysis with FISH, and neuropathological studies of surgically resected cortical tissue were performed. Both patients showed severe developmental delay with cardiovascular malformations and one of them had drug resistant epilepsy. Polymicrogyria was found in the frontal, parietal, and temporal areas, unilaterally in one patient and bilaterally in the other. Histology revealed four-layered polymicrogyria. The pathogenesis of polymicrogyria in 22q11 deletion syndrome is discussed.