In order to study the possibility of demonstrating the presence of the morbid gene among the offspring of patients with Huntington's chorea by electroencephalography before its clinical manifestation, a total of 25 such offspring were submitted to electroencephalographic study. The examination revealed initial signs of Huntington's chorea in 2, both of whom had electroencephalograms (EEGs) of the low-voltage-fast pattern. Among the 23 clinically healthy subjects, definite EEG changes were demonstrable in only one. Another one had an EEG of the low-voltage-fast type, and 5 exhibited minor changes of doubtful significance, whereas in 16 the EEGs were normal in every respect. The writer concludes that this method does not seem to be able to afford a possibility of demonstrating the presence of the morbid gene with anything approaching certainty.