Although imperfect, MRI is the best way of distinguishing type 1 lissencephaly from other, less classical lissencephalic malformations. We reported a case in which correlation of MRI and neuropathology was possible. Besides the classical radiological features of lissencephaly, i.e., agyria and excessive thickness of the cortex, an additional sign was observed: a thin cortical band, which gave high signal on T2-weighted images, represented a paucicellular and partially myelinated band, 1500 microns thick, lying under the true superficial cortex. This MRI feature could be characteristic of the particular cortical lamination observed in true type 1 lissencephaly.