Lycium barbarum, a famous Chinese medicinal herb, has a long history of use as a traditional remedy for many diseases. Polysaccharides are the most important functional constituent in Lycium barbarum fruits. In the present study, the antioxidant activity of polysaccharides extracted from Lycium barbarum fruits growing in Xin Jiang, a northwest province of China, was evaluated. Six established in vitro methods, including superoxide radical (O₂ ^-) scavenging activity, reducing power, β-carotene linoleate model, inhibition of mice erythrocyte hemolysis mediated by peroxyl free radicals, 1,1- diphenyl-2 picrylhydrazyl (DPPH) radical-scavenging, and metal chelating activity were used in our evaluation. The polysaccharides showed considerable inhibitory activity in the β-carotene–linoleate model system in a concentration-dependent manner. Further, they exhibited moderate concentration-dependent inhibition of the DPPH radical. The multiple antioxidant activity of the polysaccharides was evidenced by significant reducing power, superoxide scavenging ability, inhibition of mice erythrocyte hemolysis mediated by peroxyl free radicals, and also ferrous ion chelating potency. The data obtained in the in vitro models clearly establish the antioxidant potency of the polysaccharides extracted from Lyceum barbarum fruits.