The thyrotropin-releasing hormone (TRH) stimulation test was carried out in 100 acutely hospitalized adolescents (ages 13-17 years) with a variety of diagnoses. The test was positive (delta max thyrotropin less than or equal to 7 microIU/ml) in 36.6% of adolescents with major depression, 20.8% with conduct disorders, 17% with adjustment disorders, and 43% with substance abuse disorders. A X2 analysis of the data showed no significant difference among these four diagnostic groups. The test was negative in adolescents with attention deficit disorder and dysthymic disorder. Comparison of the six diagnostic groups with regard to the amount of thyrotropin (thyroid-stimulating hormone, TSH) response to TRH stimulation indicated that the groups with major depression and substance abuse disorders had significantly lower values of delta max TSH than the other groups. TSH values did not differ significantly between males and females. Similarly, there were no significant age differences (younger adolescents vs. older adolescents).