In this study, the total phenolic and flavonoid contents, total antioxidant capacity, free radical scavenging activities, ascorbic acid levels of the endemic Astragalus halicacabus Lam. species growing in Turkey were thoroughly evaluated. The total antioxidant capacity of the leaves was determined as 10.32±0.30 mM ascorbic acid/g, while total phenolic and total flavonoid contents were 4.29±0.12 mg gallic acid/g and 3.54±0.22 mg quercetin/g, respectively. The ascorbic acid content was measured as