The inner ear is innervated by the sympathetic nerves and the disturbance of sympathetic nervous function can induce tinnitus, dizziness and sudden deafness. The earlier assays showed the presence of tyrosine hydroxylase-like and dopamine β-hydroxylase-like immunoreactivities in mammalian cochlea. However, phenylethanolamine N-methyl-transferase-like immunoreactivities were undetectable. Although the presence of epinephrine was not detectable in the tissues of the inner ear, some authors have suggested the presence of epinephrine in the perilymph. Using high performance liquid chromatography coupled with electrochemical detector(HPLC-EC), we demonstrate in this report the presence of catecholamine in the prilymph. The results were as follows ; 1) The mean concentrations for epinephrine, norepinephrine, and dopamine were 75.1ng±5ng/ml, 3.3ng±0.5ng/ml, and 13.8ng±2.4ng/ml, respectively. 2) Epinephrine and norepinephrine in the perilymph were present at higher concentrations than in the CSF, while the opposite was true for dopamine. 3) These results suggest that epinephrine may be one of neurotransmitters of the inner ear, and further studies are necessary for elucidation of its exact role.