The present study evaluated the antioxidant activity of 21 extracts prepared from seven parts of Pistacia atlantica Desf. subsp. atlantica. (Fruits, leaves, buds, stems, roots, internal and external trunk barks) collected from Tlemcen, Algeria. Total phenolic, flavonoid and flavonol contents were determined and the antioxidant properties were measured using different assays: 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), ferric antioxidant reducing power and β-carotene bleaching assay. BHA (butylated hydroxyanisole) was used for comparison purposes. The results showed that the extracts of leaves and buds had the highest phenolic contents with 255.789 ± 4.733 and 233.946 ± 6.205 mg GAE/g DM, respectively. For the antioxidant activity, values of EC50 concentrations ranged from 0.059 to 5.712 mg/mL for DPPH, 0.015 to 3.141 mg/mL for reducing power and 0.068 to 5.021 mg/mL for β-carotene method, for all studied extracts. Analysing the phenolic composition, 10 components were identified in different parts of the plant.