A simple high performance liquid chromatographic (HPLC) method has been developed for determining malondialdehyde (MDA) in vegetable oils. MDA was reacted with dansyl hydrazine in an acidic medium, and the product, 1-dansyl-pyrazole, was determined by HPLC, using a Zorbax sil column with mixed mobile phase of n-hexane-methylene chloride. MDA can be determined as 1-dansyl-pyrazole by fluorometric detection at a level of 0.01 ppm in vegetable oils.