Zygophyllum cornutum Coss. is an endemic plant growing in the northern Sahara of Algeria. It is used in traditional medicine against diabetes, hypertension and dermatitis. The antioxidant activities of the crude hydroalcoholic extract and the organic fractions of Z. cornutum were investigated by DPPH test, ferric reducing activity and phosphomolybdenum assay. Also the content of phenols, flavonoids and tannins was estimated by spectrophotometric methods. The best DPPH scavenging activity was found in water fraction followed by chloroform fraction (IC50= 25 and 38.5 μg/ml, respectively), more effective than BHT. For the ferric reducing activity and phosphomolybdenum assay, the best activity was found in water and butanol fractions, the results were better than BHA and BHT. The content in phenolics, flavonoids and tannins may be responsible for the good activities of the plant Z. cornutum.