In 10 patients suffering from cardiac neurosis changes in plasma norepinephrine (NE) and epinephrine (E) were studied by an upright bicycle exercise and during psychological stress. Psychometric tests were also performed. 6 healthy subjects served as a control group. At exercise, no relevant differences in blood pressure and heart rate regulation between patients and controls were present. The NE and E increase was normal and similar in both groups. During psychological stress an equal plasma NE increase was seen in both groups. During recovery, however, a sustained release of NE was present in patients. It is concluded that patients with cardiac neurosis respond to psychological stress by an inappropriate sustained activation of the sympathetic nervous system.