Three groups of children were examined—chronically depressed inpatients, orthopedic inpatients screened for psychopathology, and a control group of physically and emotionally healthy outpatients. The urinary metabolites studied were norepinephrine (NE), vanillylmandelic acid (VMA), and 3-methoxy-4-hydroxyphenylethylene glycol (MHPG). Only MHPG showed a significant difference between the groups: the outpatient control group had the highest mean vaalues—1,092 μg/m2 ± 109; the depressed patients, 735 μg/m2 ± 64; and the orthopedic patients, 504 μg/m2 ± 32. The discussion centers on the possible relationship between the activity and the MHPG values in these children. VMA and NE values would seem to rule out activity as the cause of the differences seen. Finally, a theory concerning a reactive suppression of the arousal system is proposed to explain the low MHPG values in the orthopedic patients.