A marked elevation in human growth hormone (GH) following intravenous infusion of thyrotropin releasing hormone (TRH) was seen in three of seven adolescent male schizophrenic patients receiving neuroleptic drugs, and in one of five controls matched for age, sex, and developmental stage, receiving the same drugs. A positive family history for schizophrenia was noted in all three schizophrenic ‘responders' but in only one of the remaining patients. The response patterns of thyroid stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4 following TRH infusion were not significantly different in the two groups. No significant correlations were found between T3, T4, TSH, or GH response patterns and age of patient, duration of illness, medication dose or duration, weight change, or hours of sleep preceding testing.