This study was designed to examine the chemical composition and antioxidant activity of the essential oil and methanol extract of Mentha pulegium. Gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS) analysis of the oil resulted in the determination of 22 components representing 98.88% of the oil. The major constituents of the oil were pulegone (71.47%) and menthone (7.67%). Antioxidant activities were determined by three different test systems, namely, DPPH, bcarotene/linoleic acid, and reducing power assay. In the DPPH system, essential oil showed the weakest activity. In the second case, the inhibition capacity (%) of the extract was measured as 63.17% +/- 0.92 (at 2 mg/mL concentration). In the case of reducing power, methanol extract again was the strongest radical reducer when compared with the oil. As expected, the amount of total phenolics was very high in methanol extract (97.20 +/- 0.05 mu g gallic acid equivalents/mg extract). On the other hand, total flavonoid content was found as 20.88 +/- 0.04 mu g quercetin equivalents/mg extract.