1. Growth hormone secretion was assessed in nine control subjects and nine patients with Huntington's chorea.
2. Early-morning fasting plasma samples from patients with Huntington's chorea contained abnormally high concentrations of growth hormone.
3. The suppression of growth hormone after oral glucose in choreic patients, unlike the control subjects, occurred at irregular intervals after the glucose was given and was followed, again at irregular intervals, by an exaggerated rebound phase.
4. The response to intravenous insulin was not markedly abnormal in choreic patients. However, there was a significant increase in the rate of rise of growth hormone concentration in the first half an hour after the insulin injection when compared with control subjects.