A new method was proposed to determine trace copper and zinc in vegetable oils by derivative flame atomic absorption spectrometry combined with flow-injection technique. The flaw that sampling is large and matrix interference was serious in conventional Flame Atomic Absorption Spectrometry (FAAS) was overcome by flow-injection sampling technique. The sensitivity and signal selectivity were enhanced when derivative technique was used in flame atomic absorption spectrometry. The results of determinations of copper and zinc in vegetable oils were satisfactory by derivative flame atomic absorption spectrometry combined with flow-injection, which were not done by conventional FAAS or flow-injection FAAS. The sensitivities were 0.004 0 and 0.001 2 microg x mL(-1) for copper and zinc, respectively, and the relative standard deviation was 1.1% -5.1%.