Abstract The leaf essential oils (six samples) from three clones of Eucalyptus camaldulensis Dehnh. were character- ized by gas chromatography-mass spectrometry. Radical scavenging and antioxidant properties were investigated by the 1,1-diphenyl-2-picylhydrazyl (DPPH) assay and the b- carotene bleaching test. It was found that the whole essen- tial oil and its fractions had significant antioxidant effects when they were tested by each method. In the DPPH assay, the E. camaldulensis leaf oils showed IC50 inhibitory con- centrations in the range of 1.75–12.62mg/ml. In the b-
carotene bleaching test, the IC50 valued were in the range of 14.30–118.55mg/ml.