Four cases of Aicardi's syndrome are reported. The constant features of this syndrome are infantile spasms, chorioretinopathy, and agenesis of the corpus callosum. The chorioretinopathy appears to be a defect of the pigment epithelium and choroid without significant retinal involvement. Additional ocular features include microphthalmia, colobomas of the optic nerve and choroid, persistent pupillary membrane, and glial tissue extending from the disc. The cause of the syndrome is uncertain. It occurs only in females and is nonfamilial. A male lethal syndrome resulting from a gene on the X chromosome occurring as a spontaneous mutation has been suggested. The possible role of intrauterine infection needs further investigation.