ABSTRACT The antioxidant activity of 70% and 90% ethanolic extracts obtained from the aerial parts of Ajuga orientalis L. (Lamiaceae) was evaluated using the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay across six concentrations ranging from 5 to 100 μg/mL. Both extracts demonstrated concentration-dependent radical scavenging activity. The 90% ethanolic extract exhibited higher antioxidant activity (IC₅₀ = 122.09 μg/mL, R² = 0.827) compared to the 70% ethanolic extract (IC₅₀ = 160.26 μg/mL, R² = 0.832), indicating that higher ethanol concentration improves the extraction efficiency of moderately polar phenolic compounds. Gallic acid was used as a reference standard (IC₅₀ = 2.41 μg/mL, R² = 0.971). The moderate R² values for the extracts reflect natural variability in crude extract composition and fall within the acceptable range reported for plant extract DPPH assays (Brand-Williams et al., 1995). The observed antioxidant activity is attributed to phenolic constituents — including rosmarinic acid, caffeic acid derivatives, and flavonoids — known to be present in Ajuga species. These findings support the traditional medicinal use of A. orientalis in Azerbaijan and justify further phytochemical characterisation and pharmacological validation. Keywords: Ajuga orientalis L.; antioxidant activity; DPPH assay; phenolic compounds; free radical scavenging; IC₅₀; ethanol extract; Azerbaijan