Urinary epinephrine (E), norepinephrine (NE) and vanylmandelic acid (VMA), plasma cortisol and free fatty acids (FFA), respiratory and cardiovascular indices, and subjectively reported emotion were measured on successive days under conditions of stress and relaxation in 6 healthy males and 6 matched young males with perennial, mild-to-moderate bronchial asthma in remission. They had taken no medication for at least a week and no steroids for 6 months. Asthmatics, as compared to control Ss, had significantly lower urinary E values, during both stress and control periods. Initial levels of NE and VMA excretion in urine were normal; NE levels responded to stress as expected, but did not discriminate between groups. Plasma cortisol did not differ between groups in this small sample. These findings argue against a global sympathetic nervous system or adrenal cortical defect, and are consistent with the hypothesis of a specific hypothalamicadrenal medullary defect in bronchial asthma. Respiratory indices (unlike heart rate and blood pressure) differentiated between the groups: asthmatics had lower airway conductance and respiratory rate and an opposite direction of change in these indices under stress. Psychologically, asthmatic Ss exhibited a marked field independence and, although as emotionally aroused by stressors as were controls, gave evidence of inhibition of aggressive impulses.