Indonesia is known for its high biodiversity, particularly in herbal medicine, with cashew trees being one of the most used plants. Cashew leaves contain proteins, fats, carbohydrates, calcium, and vitamins B1 and B2. They are used as herbal medicine in various parts of Indonesia, including kidney disease treatment, mouthwash, and kanker disease drugs. The ethanol extract from cashew leaves contains secondary metabolite compounds such as phenolic, flavonoids, and tannins. The bioactivity of cashews includes antiviral, antifungal, antibacterial, and anti-inflammation properties. The cardanol compound from cashew leaves has the highest antioxidant activity compared to cardol and anacardic acid, with IC50 values of 3,22±0.07 ?g/ml and 0,06±0.01 ?g/mL, respectively. This research aims to isolate phenolic compounds from cashew leaves, identify their structure, and measure antioxidant activity. The study analyzed the phytochemical screening of A. occidentale leaf extracts, revealing variations in their components. Hexane extracts were positive for tannin and terpenoid compounds, while dichloromethane extracts were positive for all compounds except saponin and cardiac glycoside. Ethyl acetate extracts were positive for terpenoids and flavonoids. Methanol extracts were positive in nearly all assays except for anthraquinone. The isolated compound from A. occidentale leaf yielded a yellow powder with a melting point of 247-248?C. The crude extract had an IC50 value of 59.19 ± 2.38 ?g/mL, while the phenolic separated element had a value of 191.815 ± 1.07 ?g/mL. Flavonoids are a group of antioxidants that act as chelators and scavengers of free radicals, targeting hydroxyl and peroxyl radicals, superoxide anions, and peroxynitrites. The Anacardiaceae family species contain numerous phenolic compounds with potent antioxidant properties, which can help manage elevated free radical generation conditions. Further research is needed to determine the specific phenolic chemicals responsible for the antioxidant activity of the species and evaluate their contribution to this activity. Anacardium occidentalale L. leaves, seeds, and stem bark extracts have been found to have antioxidant and antimicrobial properties. The traditional herbal medicine of Indonesia, Jamu, is a valuable source of antioxidants and prooxidants