• We report what we believe to be the first known case of linear nevus sebaceus syndrome with infantile spasms followed by Lennox-Gastaut syndrome. The EEG revealed hemihypsarrhythmia and then asymmetrical slow spike-wave complexes. A pneumoencephalogram showed dilation and distortion of the lateral ventricle ipsilateral to the facial nevus on the left side. A computerized tomographic scan disclosed low density in the left parietotemporal region, a feature not reported previously. The findings indicated extensive lateralized cerebral lesions.