<jats:p><jats:bold>Abstract: </jats:bold> Both concentrations of total 3‐methoxy‐4‐hydroxyphenylglycol (MHPG) and 3,4‐dihydroxyphenylglycol (DHPG) in the human urine, plasma and CSF were determined with a high‐pressure liquid chromatography with electrochemical detection in order to clarify the dynamic change in these noradrenaline metabolites. Three different biological fluids were collected simultaneously from 16 orthopedic patients who were regarded clinically as substitutes for normal subjects. In the urine, the MHPG concentrations were 1.67±0.65 μg/mg creatinine (mean±S. D.) and DHPG 0.39 μg/mg creatinine±0.21. The plasma levels were 21.16 ng/ml±9.58 for MHPG, and 19.58 ng/ ml±8.13 for DHPG. The CSF levels of MHPG and DHPG were 24.08 ng/ml±8.10 and 34.76 ng/ml±11.46, respectively. The CSF levels ofthese metabolites were correlated significantly with those in the plasma (r = 0.852, p <0.001 for MHPG; r = 0.799, p <0.001 for DHPG), while no significant correlations were found between the urinary levels and either the plasma or CSF levels of these metabolites. In the urine, the MHPG levels were proportional to the DHPG levels, while the former were inversely proportional to the latter in the plasma or CSF. Neither the MHPG nor DHPG levels in the urine from depressed patients revealed to have any significant correlation withtheir clinical assessments using the Hamilton Rating Scale Score (HRS). The patients weretreated with an antidepressant active selectively on the noradrenergic system, and no significant changes in urinary excretion of these metabolites were observed before and afterthe drug treatment. These findings suggest that in the case of psychiatric disorders suchas depression, these compound levels in the plasma or CSF would provide more important information than those in the urine.