The reaction of methyl linoleatc hydroperoxides with DNA, nucleosides and DNA bases was investigated by determining the fluorescence formation in the presence of ascorbic acid and Fe2+. Methyl linoleate hydroperoxides produced significant fluorescence only with adenosine and with DNA, but not with the other nucleosides tested. Adenine also produced similar fluorescence, suggesting that the amino group at the 6-position reacted preferentially with the lipid oxidation products to produce fluorescence. The pH level did not have any distinct effect on either the intensity or spectrum of fluorescence in the range of 4.0-9.0. Among the degradation products of methyl linoleate hydroperoxides, 2-octenal and 2, 4-decadienal produced fluorescence with adenine even in the absence of FeSO4 and ascorbic acid. However, none of these carbonyl compounds produced significant fluorescence in the reaction with DNA, FeSO4 and ascorbic acid. Potassium iodide, hydroquinone, alpha-tocopherol and BHA reduced the amount moiety in DNA reacts with the secondary decomposition products of methyl linoleate hydroperoxides after strand-breaking by radical species derived from methyl linoleate hydroperoxides.