The study was undertaken to examine the content of free and conjugated forms of norepinephrine, dopamine, epinephrine in the daily urine and blood plasma of psychopathic patients during varying severity depressive disorders. To isolate the conjugated forms, hot acid hydrolysis was applied, catecholamines were measured by the procedures based on high performance liquid chromatography with electrochemical detection. Patients with the most marked clinical signs of depressions were found to have the most profound urinary and blood shortage of free forms of dopamine and norepinephrine, as compared with the controls, which was associated with the most intensive conjugation of these catecholamines. Thus, it may be supposed that disturbances of the catecholamine conjugation systems are one of the neurochemical mechanisms underlying the development of affective disorders.