The influence of short-time emotional and cognitive stimuli on autonomic functions and plasma catecholamines was investigated in 12 paranoid schizophrenics, 12 endogenous depressive patients, and 63 normal controls. The schizophrenics showed higher norepinephrine levels, depressives higher epinephrine levels; in both groups of patients most of the physiological parameters were elevated throughout the trial, showing, on the other hand, reduced responsiveness to external stimulation.