A phosphorimetric method for the determination of epinephrine was established. The method is based on measurement of the phosphorescence of the phosphorescent compound formed in the reaction of epinephrine with 2-chloro-5-nitropyridine after isolation of the compound by thin-layer chromatography. The method can be applied to the determination of epinephrine in the concentration range from 2 to 20 μg/ml, and interfering substances such as norepinephrine, tyrosine, metanephrine, normetanephrine, phenylalanine, 3, 4-dihydroxyphenylalanine, and 3-hydroxytyramine are easily removed.