To clarify the degradation pathway of acrinol by light, isolation and identification of acrinol degradation products (ANDP) were attempted. ANDP-2, one of the ANDPs, was isolated by extraction with methanol from cloths dampened with acrinol solution, and purified by column chromatography on Diaion HP-10, Sephadex LH-20 and G-25. The structural elucidation of ANDP-2 was examined by infrared, 1 H-NMR, 13 C-NMR and Fast atom bombardment mass (FAB-MS) spectra studies. From the spectroscopic data, the structure of ANDP-2 was determined to be 4-amino-6-ethoxyl-2,3-dicarboxyquinoline, that was found to be a novel degradation product of acrinol by light. The solution of ANDP-2 has fluorescence with a blue color, though that of acrinol has fluorescence with green. ANDP-2 did not show growth inhibition at a concentration of 100 µg/ml against Gram-positive, -negative bacteria, yeast and fungi.