The role of the corpus callosum in the relationship between the EEGs of the two cerebral hemispheres was studied by comparing 3 infants with congenital agenesis of the corpus callosum with a group of neurologically normal infants. Coherence functions were computed for symmetrical pairs of EEG derivations; in the frequency bands below 4 Hz they were in general much lower in the acallosal infants than in the normals.