A mother and daughter with agenesis of the corpus callosum are reported. There have only been 11 prior case reports of the familial occurrence of agenesis of the corpus callosum in the absence of extracranial malformations. Most of these reports have described familial occurrence among siblings. The present communication is only the second description of a parent and child with agenesis of the corpus callosum. A review of the published cases of familial syndrome unrelated agenesis of the corpus callosum indicates that both mental, developmental and neurologic disorders in cases involving parent and child are milder than those in cases involving siblings. Of additional interest, electroencephalography performed in this patient during sleep, frequently revealed bilateral asynchronous sleep spindles, supporting the hypothesis of previous investigators that the synchronicity of sleep spindles requires intact intercerebral commissures.